LAI TUN YU AND ANOTHER v. NG HUNG MING as the EXECUTOR OF THE ESTATE OF LAU YING HING, DECEASED AND ANOTHER

DCCJ 270/2022

[2025] HKDC 2132

IN THE DISTRICT COURT OF THE

HONG KONG SPECIAL ADMINISTRATIVE REGION

CIVIL ACTION NO 270 OF 2022

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BETWEEN

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JUDGMENT

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Introduction

1.  This is the trial of a water leakage case concerning a flat located on the 2^nd Floor, No. 81 Kai Tak Road, Kowloon, Hong Kong (the “2/F Unit” and a flat on the 3^rd Floor (“3/F Unit”) that is immediately above the 2/F Unit of the same building.

Background

2.  The Plaintiffs are the registered owners of the 2/F Unit.

3.  On 27 May 2005, the late Madam Lau Ying Hing (“Madam Lau”) became the registered owner of the 3/F Unit. Madam Lau passed away on 17 November 2020. Probate was granted to Mr Ng Hung Ming, the 1^st Defendant, as the executor of Madam Lau’s estate.

4.  By an agreement for sale and purchase dated 29 December 2021, the 1^st defendant sold the 3/F Unit to the 2^nd Defendant.

5.  On 19 January 2022, the Plaintiffs commenced the present action against the 1^st Defendant for negligence and nuisance based on alleged water leakage from the 3/F Unit to the 2/F Unit. They claimed damages and injunctive relief against the 1^st Defendant.

6.  By an assignment dated 29 July 2022, the 3/F Unit was assigned to the 2^nd Defendant, and she became the registered owner of the 3/F Unit.

7.  On 26 September 2023, the 2^nd Defendant was added as the additional defendant in this case.

8.  The Plaintiffs and the 1^st Defendant subsequently reached a settlement and filed a consent summons on 19 February 2025. The consent summons was approved by DDJ Louise Chan on 8 May 2025.

9.  As such, it remains for this trial to deal with the Plaintiffs’ claims against the 2^nd Defendant only. Unless the 1^st Defendant is specifically mentioned, the word “parties” in this judgment generally refers to the Plaintiffs and the 2^nd Defendant only.

10.  Moreover, it is the Plaintiffs’ case that the 2/F Unit is no longer affected by water leakage (discussed further below). Therefore, the Plaintiffs are only claiming damages but not the relief of injunction.

The parties’ respective case

11.  The two subject flats in this case are located within a relatively old Chinese building (唐樓). There is no dispute that the Plaintiffs have modified the internal layout of the 2/F Unit such that it is divided into 3 rooms (Rooms A, B and C), each is equipped with a small toilet, to be rented out to different tenants. In contrast, no or no material modification has been made to the 3/F Unit.

12.  The Plaintiffs’ pleaded case is that the kitchen in the 3/F Unit is located right above Room C in the 2/F Unit, and the bathroom in the 3/F Unit is located above Rooms B and C of the 2/F Unit. The 2^nd Defendant, on the other hand, denied in her defence that the bathroom in the 3/F Unit is above Room B of the 2/F Unit. However, at trial, no significant issue seemed to turn on this. Essentially, the parties are in agreement that the kitchen and the bathroom in the 3/F Unit are above Room C of the 2/F Unit.

13.  Below is the parties’ agreed diagram showing the layout of the 2/F Unit after the modifications (with Rooms A, B, and C), and the corresponding layout of the 3/F Unit.

14.  The Plaintiffs aver that, starting from about October 2016, water had been leaking from the 3/F Unit to the 2/F Unit, causing damage to the 2/F Unit and loss to the Plaintiffs. The water leakage problem persisted after the assignment of the 3/F Unit on 29 July 2022 from the 1^st Defendant to the 2^nd Defendant. As of 2 August 2023, there was still water leakage to the 2/F Unit.

15.  The 2^nd Defendant does not admit that the 3/F Unit was the source of any water leakage in the 2/F Unit. The 2^nd Defendant’s surveyor had examined the relevant premises and observed that there were cracks and holes in the building’s external walls which might likely be the cause of water penetrating into the 2/F Unit.

The parties’ factual witnesses

Madam Liu’s evidence

16.  At trial, Madam 廖彩菊 (“Madam Liu”), who is the mother of the Plaintiffs, gave evidence for the Plaintiffs. According to Madam Liu, the Plaintiffs acquired the 2/F Unit from their grandfather on 23 February 2005. For about 1 or 2 years thereafter, Madam Liu’s mother-in-law and sister-in-law resided at the 2/F Unit. In around 2007 or 2008, the Plaintiffs decided to partition the 2/F Unit into 3 rooms for rental purpose. Madam Liu was entrusted by the Plaintiffs to deal with all matters related to the 2/F Unit.

17.  In about October 2016, Madam Liu received a complaint from the tenant of Room C that there was water leakage in the room. The tenancy agreement was terminated on 30 May 2017 by a written notice and the water leakage problem was stated by the tenant as the reason for termination. Madam Liu then made a complaint with the building’s Incorporated Owners (“IO”) and subsequently to the Joint Office (“JO”) of the Buildings Department (“BD”) and the Food and Environmental Hygiene Department (“FEHD”). The JO had carried out a number of inspections and made several reports between June 2017 to April 2023.

18.  In addition, the Plaintiffs (acting through Madam Liu) have also engaged Mr Wong Shun Tai Stewart (“Mr Wong”) to inspect and investigate on the possible sources of water leakage.

19.  As the water leakage problem persisted, the Plaintiffs commenced the present action against the 1^st Defendant and subsequently the 2^nd Defendant. It was only in around April 2024 that the 2/F Unit ceased to have any water leakage problem.

20.  My overall assessment of Madam Liu’s evidence is that it was logical, reasonable and generally consistent with the contemporaneous documents. I accept her evidence.

2^nd Defendant

21.  The 2^nd Defendant gave evidence in court. She said that she was living in the neighbourhood of the subject building and came to know the 1^st Defendant and the sale of the 3/F Unit.

22.  Prior to her purchase of the property, the 1^st Defendant had informed her of the water leakage complaint and the repair works that had been carried out by the 1^st Defendant to resolve the problem. In particular, the 1^st Defendant told her and she saw that the 1^st Defendant had engaged workmen to carry out certain repair works, namely (1) changing the water tap above the sink in the kitchen, (2) replacing the water filter (隔水格) and (3) replacing the piece of rotten wood with cement near the foot of the kitchen cabinet. She thought that such repair works would be sufficient to rectify the water leakage problem in the 2/F Unit.

23.  The 1^st Defendant also showed her the JO’s letter dated 30 June 2022 (“JO June 2022 Letter”) which stated, inter alia, that there was still water leakage problem in the 2/F Unit but the source of such leakage could not be identified. Her understanding was that the 1^st Defendant had properly dealt with the water leakage problem insofar as the 3/F Unit was concerned, and even though there was still water leakage in the 2/F Unit, it was probably due to some other causes unrelated to the 3/F Unit. Therefore, she decided to purchase the 3/F Unit for rental purpose.

24.  After her purchase of the 3/F Unit, the 2^nd Defendant arranged water pressure test to be performed on the flat’s fresh water pipes, and she was told that the pipes were fine and there was no need to replace them. She also repaired the concrete spalling areas in her flat. Having carried out these repair works and with her understanding mentioned above, she leased out the 3/F Unit in December 2022.

25.  In around April 2023, in response to a separate complaint (not from the Plaintiffs or Madam Liu) that a fresh water pipe from the 3/F Unit was leaking to the external wall on the 1/F podium, the 2^nd Defendant carried out certain repair works. In June 2023, she texted Madam Liu if the 2/F Unit water leakage problem was by any chance improved as a result of the repair works. In August 2023, Madam Liu replied that there was no improvement.

26.  The 2^nd Defendant emphasised that she has all along been ready and willing to cooperate. In particular, she has cooperated in helping the Plaintiffs locate the source of water leakage by providing access to the JO and the Plaintiff’s expert to carry out various tests and investigations in the 3/F Unit.

27.  I have found the 2^nd Defendant’s oral testimony generally credible and consistent with the contemporaneous documents. In any event, as will be seen below, the majority of the issues in this case do not turn on the witnesses’ credibility. Instead, they hinge on the objective assessment of the documentary evidence before the court.

The parties’ expert witnesses

Mr Wong

28.  Mr Wong gave evidence on behalf the Plaintiffs. He said that he has given evidence as an expert in court for more than 200 water leakage cases. While in some cases his qualifications and evidence were criticised, he said that his evidence as a water leakage expert was accepted in all the other cases.

29.  Mr Billy Poon, counsel for the 2^nd Defendant, drew to the court’s attention that the qualifications and reliability of Mr Wong were subject to judicial scrutiny and criticism on a number of occasions.

(i) In Hui Ling Chun v Siu Mak Ying, unreported, DCCJ 10294/2001, 3 March 2004, HH Marlene Ng (as she then was) held that even though the opposing party did not challenge the expert capacity of Mr Wong, his qualifications and experience were relevant in assessing the weight of his evidence. The learned Judge noted that the various institutions of which he was a member had no statutory recognition in Hong Kong and their membership requirements were unknown (at §§28-30, 34).

(ii) In Yan Wing Fai Rick v Century One Ltd, unreported, DCCJ 2773/2009, 2 February 2011, DDJ Harold Leong (as he then was) noted that Mr Wong’s CV was challenged, but the court was less impressed by an expert’s CV than with the soundness of opinion, in particular the methodology of his investigation and whether his opinion was based on sound scientific model (at §§43-44). It should be noted that, in that case, Mr Wong’s evidence was preferred by the learned Judge over the other expert’s (at §§53-79).

(iii) In Hui Ling Ling v Sky Field Development Limited, unreported, HCA 35/2007, 8 May 2012,[1] Recorder Rimsky Yuen SC commented that the learned Judge’s observations in Hui Ling Chun remained valid, as it remained the fact that Mr Wong was at all material times not a registered or chartered engineer, nor was he a registered or chartered surveyor (especially in the context of building survey). Moreover, the learned Recorder also found that many of the observations made by Mr Wong were no more than bare assertions without detailed or solid reasons or analyses. Although Mr Wong’s evidence was not ruled as inadmissible on ground that he was not qualified to be an expert for the purposes of the case, the court had serious reservations about the reliability of his evidence (at §§39-43).

(iv) In Wong Ping Chun v Giant King Corp Ltd, unreported, DCCJ 4020/2012, 16 March 2016, DDJ Phillis Loh (as she then was) held that, leaving aside the question of academic and professional qualifications, and even accepting his evidence of profound experience as a water leakage expert, and that he possessed qualifications equivalent to those of a registered or chartered surveyor or engineer, she found the evidence of Mr Wong unreliable given his approach in investigating the water leakage in that case, and in view of the contradictory and speculative comments and conclusions made by him (at §56).

(v) In a more recent case of Wu Hucheng v Tian Jiong & Another [2024] HKDC 1902, DDJ Aidan Tam referred to the judicial comments from the above cases. Although it was noted that Mr Wong has no qualification as a surveyor whether in Hong Kong or overseas, the learned Judge adopted the approach in the above cases and decided not to rule Mr Wong’s evidence as inadmissible simply because of the doubts over his professional qualifications. Instead, the reliability of his evidence should be considered in light of the methodology used, exaggerations (if any) and the adequacy of analysis for his observations or conclusions. On the facts of that case, the learned Judge criticised the methodology and analyses of Mr Wong and held that a number of his conclusions were unsafe (at §§137-150).

30.  During cross-examination, Mr Wong accepted that he is neither a registered professional surveyor under the Surveyors Registration Ordinance, Cap. 417, nor a member of the Hong Kong Institute of Surveyors established under The Hong Kong Institute of Surveyors Ordinance, Cap. 1148. However, he said that his qualification as a “Chartered Association of Building Engineer, UK (Reciprocal recognition with ARICS)” is reciprocally recognised in Hong Kong. Mr Poon pointed out that the same assertion by Mr Wong had been rejected and criticised by DDJ Kay Seto in Yung Yuk Lin v The Incorporated Owners of Keymount Lodge, unreported, DCCJ 4059/2018, 12 July 2021:

“43. However, it is pertinent to note that there is no professional organisation named “Royal Chartered The Australian Institute of Building [sic]” or “Chartered Association of Building Engineer, UK [sic]”, and the correct names should be “Australian Institute of Building” and “Chartered Association of Building Engineers” respectively. More importantly, as a matter of fact, neither the Australian Institute of Building nor the Chartered Association of Building Engineers has any reciprocal recognition agreement with HKIE, contrary to Mr Wong’s testimony.

44. In my view, Mr Wong, who professed to be the most senior engineer in Hong Kong with a wealth of experience in testifying as an expert witness in court proceedings, did not provide a full and accurate picture of his professional qualifications at this trial. He is well aware that, as an expert witness, he has an overriding duty to help the court impartially and independently on matters relevant to his area of expertise: see paragraph 2 of the Code of Conduct. He is also aware that his qualifications were subject to judicial criticism on previous occasions. Yet, he still provided incorrect information to this court on his own qualifications, which led to some confusion as to the status and quality of those qualifications, and is in my view unsatisfactory.”

31.  Apart from Mr Wong’s qualifications, Mr Poon also challenged the reliability and accuracy of his opinion, on the basis of his failure to properly read the water meter in the flow meter tests (more on this below) and his omission of weather data in all his reports in this case, despite his evidence that he had included weather data in all the other court cases that he has done. Mr Poon asked the court to reject Mr Wong’s opinion.

32.  Ms Sezen Chong, counsel for the Plaintiffs, emphasised that no objection has ever been made to the appointment of Mr Wong as the Plaintiffs’ expert in this case, and his status as an expert here is not open to challenge. She submitted that Mr Wong’s conclusions were consistent with or supported by the test results of other experts or reports in this case, and she urged the court to accept Mr Wong’s expert evidence.

Mr Leung Ka Chun (“Mr Leung”)

33.  Mr Leung gave expert evidence on behalf of the 2^nd Defendant. He is a chartered building surveyor, a chartered builder and a chartered building engineer. Since 2013, he has been the managing director of Silver Consultants Engineering Ltd. Mr Leung’s professional qualifications are unchallenged.

34.  I accept Mr Poon’s submission that Mr Leung that he readily accepted points which were against the 2^nd Defendant. For example, he has no hesitation to address the court on the limitation of the dye test. However, having considered the data and analyses in his reports as well as his oral testimony, I am unable to accept certain conclusions that he made in this case. This will be discussed further below.

Mr Cheung Hoi Tat Peter (“Mr Cheung”)

35.  For the sake of completeness, Mr Cheung was an expert witness engaged by the 1^st Defendant in this case. The trial bundles also contain an expert report of Mr Cheung and joint reports with Mr Cheung’s comments. As settlement has been reached between the Plaintiffs and the 1^st Defendant, Mr Cheung did not give oral evidence at the trial. However, in the course of their submissions, the parties have referred to certain comments made by Mr Cheung in his reports, and I will consider them in so far as it is necessary and fair to do so.

My overall view on the evidence of Mr Wong and Mr Leung

36.  First of all, I respectfully echo the observations and comments made by the court in all the cases mentioned in paragraphs 29 and 30 above. It is baffling that despite the criticism made by the court in Yung Yuk Lin (supra), Mr Wong in this case still maintained his assertion that his qualification as a “Chartered Association of Building Engineer, UK (Reciprocal recognition with ARICS)” is reciprocally recognised in Hong Kong. It appears to me that Mr Wong is either unaware of his duty to provide the court with true and accurate information about his qualifications (despite his participation as an expert in many court cases), or he could not care less about the accuracy of what he says. Either way, it casts serious doubt over the reliability of Mr Wong’s evidence.

37.  Having said that, though, I would not hold that Mr Wong’s evidence is inadmissible solely because of his qualifications. As DDJ Harold Leong (as he then was) rightly said in Yan Wing Fai Rick (supra), adducing expert evidence in court is not a battle of CVs. The court is not bound to accept the evidence from an expert with the more impressive CV, otherwise it would effectively give the most eminent expert the licence to state whatever he liked and expect the court to accept it without question. However, Mr Wong’s qualifications will be relevant in assessing the reliability and weight of his evidence, in particular where there are competing explanations and analyses.

38.  Having considered all the reports filed by the two experts and their oral testimonies, my overall view is that both of their evidence is unsatisfactory. There is an air of sloppiness in the way they carried out the tests, performed the analyses and reached their conclusions.

39.  For example, on Mr Wong’s part, he did not include any weather data in any of the reports, where there is no dispute that it is an important piece of background information when considering moisture content in water leakage cases. As mentioned above, it is his evidence that he had included weather data in all the other court cases in which he was involved but no explanation was given as to why he had omitted to do so here. Secondly, when he performed the spray water test on the building’s external wall, there is no record on the location and size of the affected areas, and he did not tabulate the results by each of the affected areas. Instead, he only produced certain photos purporting to show the moisture contents before and after the test. This is highly unsatisfactory to say the least.

40.  As for Mr Leung, although he concluded that the cracks and holes in the building’s external walls were likely the cause of water leakage in the 2/F Unit, such a conclusion was solely based on his visual observation of the external walls. He did not perform any test, such as spray water test, on the external walls to verify his view. As a matter of common sense, not all cracks and holes in the external walls would inevitably cause water penetration into a flat. Much would depend on the size, depth and location of such cracks and holes. For example, if the cracks are only superficial and above the waterproof layer of the building’s envelope (if there is any), it is difficult to see why the mere presence of such cracks would lead to water penetration. No further investigation was carried out by Mr Leung to verify or substantiate his conclusion. While it is not the 2^nd Defendant’s burden to positively prove that the 2/F Unit’s water leakage (if any) came from the external walls, an expert witness is expected to exercise due diligence and reasonable endeavours before he gives a certain suggestion and, a fortiori, reaches a certain conclusion. I do not think Mr Leung has met such an expectation in this regard.

41.  In the context of expert opinions, the court is not to be bound by the opinion or conclusion expressed by an expert witness, even if the expert opinion is not contradicted or where the experts appear to be in agreement, and can and is obliged to make its own independent judgment upon considering all the materials available: Grand Wayfair Investment Co Ltd v Chan Yung Kan, unreported, CACV 238/2013, 26 September 2014 at §§37-44.

42.  Here, I do not prefer the evidence of a particular expert over that of the other. When considering the weight of their evidence and opinions, I will critically review the aptness of methodology, the soundness of the analyses and the reliability of their conclusions, and I will make my own independent judgment based on all the materials before me.

The agreed issues

43.  The parties agreed that the following issues are to be determined at trial:

(i) whether there was indeed water leakage in the 2/F Unit and, if so, at which areas of the 2/F Unit;

(ii) whether the source of water leakage in the 2/F Unit was from the 3/F Unit or from the external wall of the building or from unknown source;

(iii) was there any continued water leakage post the sale and purchase date on 29 December 2021 for which the 2^nd Defendant is liable; and

(iv) the quantum of damages.

44.  These issues will be discussed in turn below.

Issue (1) Whether there was water leakage in the 2/F Unit

45.  The Plaintiffs’ case is that the 2/F Unit has suffered from water leakage since as early as October 2016. The 2^nd Defendant does not admit such an allegation, and puts the Plaintiffs to strict proof thereof: see 2^nd Defendant’s Defence §4.

46.  Based on the incontrovertible evidence and the agreed chronology filed by the parties, there can be no doubt that at least as from November 2020, the 2/F Unit was confirmed to have suffered from water leakage.

Date	Event
10 Nov 2020	Inspection Report issued by a consultant (P2H Design Associates Ltd) employed by the JO for the inspections conducted on 28 August 2020, 16 September 2020 and 4 November 2020, there was water leakage in Room C of the 2/F Unit and the source was identified as infiltration from the floor slab of bathroom and floor slab of kitchen in the 3/F Unit.
3 Dec 2020	JO wrote to the Plaintiffs that its consultant had conducted the dyed water test and concluded that the waterproof facilities of the kitchen and the bathroom of the 3/F Unit were defective, causing water to seep from the 3/F Unit to the 2/F Unit.
23 Sep 2021	JO issued an Abatement of Nuisance Notice to the 1st Defendant.
29 Dec 2021	The 2nd Defendant purchased the 3/F Unit.
18 Jan 2022	An officer from JO attended the 2/F Unit and found that the dampness of the ceiling to be at 100%.
10 May 2022	A consultant (Modern Testing Consultants Limited) employed by the JO concluded that while rain water leakage from external wall was ruled out, water leakage was noted at grid points or zones corresponding to the ceiling of Room C of the 2/F Unit.
12 May 2022	Mr Cheung as the 1st Defendant’s expert rendered a report on a water ponding test result and concluded that there was green-coloured water leaked through the marble curb at the toilet of the 3/F Unit onto the corridor of the 3/F Unit and penetrated down to the 2/F Unit. The defective marble curb was subsequently repaired. Attached to the report are photos showing the “damaged areas” affected by water leakage in the 2/F Unit, which are the walls and ceilings of Rooms B and C.
30 Jun 2022	Letter issued by JO stating that after the issuance of the Abatement of Nuisance Notice, JO had inspected the 3/F Unit and found that renovation had been done, but there was still water seepage and the source was unknown.
29 Jul 2022	The 3/F Unit was assigned to the 2nd Defendant who became the registered owner.
7 Feb 2023	Letter by JO that it had conducted drainage dyed test in the 3/F Unit on 23 December 2022 but was unable to ascertain the source of the water seepage. But since there was still water seepage in the 2/F Unit, JO would consider engaging professionals to conduct further investigation.
21 Mar & 18 Apr 2023	A consultant (Modern Testing Consultants Limited) employed by the JO inspected the 2/F and 3/F Units and noted moisture content between 35% and 80% in Room C. While the source of seepage was uncertain, the consultant ruled out drainage, water supply pipes and building envelope as possible water sources.
19 & 21 Sep 2023	Joint inspection by Mr Wong and Mr Leung where both experts agreed that water molecule had been trapped at the ceiling slab and walls of Room C and Room B and there were large scale concrete spalling, debonding, plaster and finish blistering and peeling on the ceiling and the wall of Room C and Room B.
25 Sep 2023	Report by Mr Leung on his inspection of the 2/F Unit and 3/F Unit on 19 and 21 September 2023, noting that before the tests were carried out, (1) 11 out of 12 test points on the upper-boundary wall in Room C had moisture content of over 35%;[2] (2) 10 out of 24 test points on the ceiling of Room C had moisture content of over 35%; (3) 3 out of 4 test points on the lower right ceiling of Room B had moisture content of over 35%; (4) 2 out of 2 test points on the right wall of Room B had moisture content of over 35%; and (5) None of the test points on the ceiling of the corridor outside Room C had moisture content of over 35%.
Apr 2024	Mr Wong inspected the 2/F Unit again and commented that there was no more leakage. He did not prepare any report for this inspection.

47.  Thus, it can be seen that both the independent consultants from the JO as well as the Defendants’ experts had concluded from their inspections and investigations that there was water leakage in the 2/F Unit at least from November 2020 to 21 September 2023 (last date of Mr Leung’s inspection). It appears that the affected areas are the ceiling and walls of Room C, and certain part of the ceiling and walls of the bathroom area in Room B (which is contiguous with part of Room C).

Issue (2) The source(s) of water leakage

48.  It is well established that in water leakage cases, there is no presumption that leakage was necessarily caused by the flat above, and the doctrine of res ipsa loquitur does not apply in water leakage cases. It is not for the defendant to identify the source of leakage or to prove that it did not come from the defendant’s flat. The onus is on the plaintiff to establish that the leakage originated from the defendant’s flat: Hui Ling Ling v Sky Field Development Limited, CACV 122/2012, 22 March 2013 at §42.

49.  A plaintiff will not be able to discharge his burden of proof if the source of water leakage cannot be determined, or there are other likely water sources: Loke Yuen Jean Tak Alice v Wong & Others, HCA 495/2012, 1 August 2019 at §52. On the other hand, so long as the defendant’s property is proved to be a source of water leakage in the plaintiff’s property, subject to the issue of knowledge, he may be held liable even if there might be other leakage paths: 皇河實業有限公司 v Wan Chiu Yuen, DCCJ 4448/2011, 20 April 2015 at §295.

50.  The issue here is whether the water leakage originated from the 3/F Unit or the external walls of the building. The Plaintiffs have postulated two sources of water leakage from the 3/F Unit to their property. First, they attribute the water leakage to long-term fresh water pipe leakage in the floor and walls of the corresponding areas above Room B and Room C. Further or alternatively, they suggest that the waterproof membrane in the floor slab of the bathroom and kitchen area was defective such that water was able to penetrate down to the 2/F Unit.

Fresh water pipes

51.  The Plaintiffs rely on the results of the flow meter tests conducted by Mr Wong to support their case that the fresh water pipes in the 3/F Unit was a source of leakage.

52.  The mechanism of the test is to observe if there is any movement of the water meter when all the water taps within the flat are turned off, ie. no one is using water. According to Mr Wong’s evidence in court, if the water meter has no movement, then it is conclusive evidence that there is no leakage from the water pipes. But if there is movement, it may suggest that there is leakage and one factor for consideration is the rate of flow. Generally, a slow and steady flow would point to the presence of leakage.

53.  Mr Wong conducted a total of 5 flow meter tests in this case. The first two tests took place on 3 November 2021 and 21 March 2022. Strictly speaking, the results of these two tests do not concern the 2^nd Defendant, as they were conducted before the 2^nd Defendant became the registered owner of the 3/F Unit and it is common ground that the 1^st Defendant had carried out certain repair works prior to the transfer of ownership. Suffice it to say that in those two tests, Mr Wong noted some movements in the meter reading and he concluded that there was water leakage from the fresh water pipes. Such conclusion was disputed by Mr Cheung in a joint report[3] and also heavily criticised by Mr Poon.[4]

54.  Mr Wong conducted his third flow meter test on 1 August 2022 for 1 hour and observed no movement of the meter for the 3/F Unit. Based on Mr Wong’s evidence in court, this conclusively shows that as of 1 August 2022, there was no leakage from the fresh water pipes.

55.  On 21 September 2023, Mr Wong conducted the fourth flow meter test where the following readings were recorded:

Time	Water meter reading[5]
11:28	XXXX853.25
12:04	XXXX864.35
13:13	XXXX866
13:14	XXXX866

56.  Based on these figures, Mr Wong made the following comment:

“The fresh water consumption meter of ‘3^rd Floor’ kept slowly moving forward from XXXX853.25 at 11:28, 864.35 at 12:04, XXXX866 at 13:13 to XXXX866 at 13:14 on 21.9.2023 when no one was at home to use water proving leakage in fresh water pipes concealed in wall/floor of bathroom / kitchen of ‘3^rd floor’. Water leaks from the fresh water pipe concealed in floor / wall of bathroom / kitchen of ‘3^rd floor’ to ‘2^nd floor’ situate ‘3^rd floor’ beneath causing the seepage damage to ceiling and walls of Room C and Room B of ‘2^nd floor’.” (original emphasis)

57.  During cross-examination, Mr Wong was asked on how to read the water meter properly and he told the court that the unit for the last integer (e.g. the “3” in the first reading of XXXX853.25 above) should be cubic metre (i.e. 1 metric ton or 1000 litres). Thus, the amount of outflow from 12:04 to 13:13 would be 11.1 cubic metres or 11,100 litres within 36 minutes.

58.  On such evidence, Mr Poon had a few criticisms. Firstly, he argued that Mr Wong’s reading of the water meter is grossly incorrect by 1000x and this shows that Mr Wong is incompetent as an expert since he did not even know how to read the water meter correctly. An outflow of 11,100 litres of water within 36 minutes is by no means slow and Mr Wong’s reading of the meter defies common sense.

59.  In his closing submissions, Mr Poon referred to the Meter Reading Guidelines issued by the Water Supplies Department, which states that the relevant unit for the last digit should be litre, not cubic metre as suggested by Mr Wong. Thus, the amount of water that was said to have leaked should be 11.1 litres, not 11,100 litres (or 11.1 cubic metres).

60.  Ms Chong objected to Mr Poon’s reference to the Meter Reading Guidelines, on the basis that none of the experts (in particular Mr Wong) was cross-examined on the document.

61.  I do not see how the reference to the Meter Reading Guidelines is unfair or otherwise prejudicial to the Plaintiffs’ position. While I accept that Mr Wong was not specifically asked about the Meter Reading Guidelines, Mr Poon did cross-examine him on the unit for each of the digits in the water meter and suggest to Mr Wong that the proper unit for the last integer should be litre, not cubic metre. Yet Mr Wong maintained his evidence. Moreover, since the Plaintiffs heavily rely on the flow meter tests to support their case that the 3/F Unit’s fresh water pipes were a source of leakage, it is important for this court to have a proper understanding of the readings. The Meter Reading Guidelines, being an official guideline issued by the Water Supplies Department on how to read water meters and the proper units for each digit, is helpful to the court for the purpose of putting the test results in proper context. Further, I note that in the joint reports, Mr Leung has also used the same unit as that in the Meter Reading Guidelines when he commented on the flow meter tests, and this was not challenged by the Plaintiffs’ counsel or expert. For all these reasons, I accept the Meter Reading Guidelines as a reference and I adopt the unit of litre for the last integer.

62.  The second criticism made by Mr Poon in respect of this test is that it was conducted in “dubious” circumstances”. The joint survey of Mr Wong and Mr Leung was conducted on 19 and 21 September 2023. According to Mr Leung’s oral evidence in court, the flow meter test was not set out in their list of tests to be conducted. No tests were supposed to be conducted on 21 September 2023 and on that day the two experts mainly observed the results of the tests conducted two days ago. After all the results were observed and recorded, Mr Leung left the premises and only his assistant stayed behind to clean up and collect the equipment. According to Mr Leung, it was under these circumstances that Mr Wong suddenly conducted the flow meter test on his own volition and without any prior notice to Mr Leung. Mr Poon therefore questioned the fairness and reliability of the test results.

63.  Not surprisingly, Ms Chong for the Plaintiffs did not accept the version of events given by Mr Leung in cross-examination. To be fair to the Plaintiffs, Mr Leung has never mentioned in any of the reports that this flow meter test was conducted unilaterally by Mr Wong in the absence of Mr Leung without prior notice. All that Mr Leung has commented in the reports was that one cannot confirm whether someone was using water at the 3/F Unit and whether all the water taps were turned off at the time of testing. As a result, Mr Wong was not cross-examined on the circumstances under which this fourth flow meter test was conducted and it would not be fair for the court to simply accept Mr Leung’s testimony in this regard.

64.  In any event, leaving aside Mr Leung’s presence and/or prior knowledge of the flow meter test, I think there are a number of issues which render the results unreliable. Firstly, other than Mr Wong’s bare assertion, there is no objective evidence or confirmation that no one was using water and all the water taps were shut in the 3/F Unit at the time of testing. Without such a confirmation, one simply cannot rely on the meter movements and suggest the possibility of leakage (instead of usage). This is particularly the case when the water flow recorded by Mr Wong was neither slow nor steady as he suggested. During the 36 minutes from 11:28 to 12:04, there was an outflow of 11.1 litres, which translates to 0.3083 litre/minute (or 308.3 ml/minute) and this does not appear to be “slow” in the context of leakage. On the other hand, during the 69 minutes from 12:04 to 13:13, there was only an outflow of 1.65 litres and the rate of flow was only 0.0239 litre/minute (or 23.9 ml/minute). There is a difference of about 13 times between the two rates and this is by no means a “steady” flow.

Time	Time difference	Reading[6]	Amount	Rate per min
11:28	-	XXXX853.25	-
12:04	36 mins	XXXX864.35	11.1L	0.3083L/min
13:13	69 mins	XXXX866	1.65L	0.0239L/min
13:14	1 min	XXXX866	0	0

65.  When cross-examined on why there was such a big difference, Mr Wong said that it might be due to water usage of other units that affected the water pressure, or there was sand or debris in the water pipe and therefore it was necessary to “check a few times”. Therefore, even on Mr Wong’s own evidence, one simply cannot conclude from this one test that there was leakage in the fresh water pipes within the 3/F Unit and further tests would need to be performed to confirm leakage.

66.  Another aspect which casts doubt on the reliability of the test results is the location of the water meter. Mr Wong told the court that the water meter of the 3/F Unit is located on the ground floor inside a shop unit. The outgoing pipe from the water meter extends above and reaches the 3/F Unit through the courtyard area. It then passes through a master switch right outside the 3/F Unit kitchen and enters into the 3/F Unit through the external wall. There is no evidence that Mr Wong had checked if (1) the meter movements were caused by any leakage of pipes before entering the 3/F Unit and (2) the location of any such leakage was capable of causing water to seep into the 2/F Unit.

67.  Furthermore, as both Mr Leung and Mr Cheung have commented, flow meter tests alone are insufficient to ascertain any leakage in the fresh water pipes, and water pressure tests to the water pipes inside the 3/F Unit would need to be performed as a cross-check. This does not seem to be disputed by Mr Wong.

68.  All in all, I do not think there is sufficient basis for Mr Wong to suggest from this flow meter test that there was leakage from the 3/F Unit fresh water pipes.

69.  Mr Wong conducted the fifth flow water test on 3 April 2024 with Mr Cheung and Mr Leung. The meter reading between 11:28 and 12:27 (59 minutes) stayed at XXXX809, which means that there was no leakage in the fresh water pipes. Mr Wong asserts, without any evidence, that the pipes were repaired at the 3/F Unit after his last inspection on 21 September 2023. This is denied by the 2^nd Defendant, who maintains that she only repaired her water pipes in response to the 1/F podium complaint in April 2023 and there were no other repair works afterwards.

70.  In any event, as a matter of reality-check, the moisture content readings across the ceiling of Room C do not seem to be compatible with a steady and/or prolonged leakage of fresh water. In Mr Leung’s opinion, which I accept as reasonable and logical, if there is any leakage in the fresh water pipes which are normally pressurised, the leakage would be continuous around the clock, and water dripping would be observed after a certain period of time. Moreover, even a single point of leakage would spread to a large area, causing saturation of moisture across the concrete slab below. As the evidence shows, however, there was no such dripping in the 2/F Unit and the moisture contents as recorded in the ceiling of Room C before the ponding tests varied to a large extent.[7]

71.  Moreover, for the purpose of completeness, I should also note that fresh water pipes within the 3/F Unit were not suggested to be a source of leakage in any of the JO reports.

72.  Thus, having considered all the materials before me, I do not think there is sufficient evidence to show, on the balance of probabilities, that fresh water pipes in the 3/F Unit were a source of leakage to the 2/F Unit.

Waterproof membrane

73.  In addition to fresh water pipes, the Plaintiffs argue that water seeped through the floor slabs of the 3/F Unit (primarily in the bathroom and kitchen areas) to the ceiling and walls of Room C and Room B, possibly due to defects in the waterproof membrane in the floor slabs.

74.  To support this argument, the Plaintiffs rely on the dye ponding tests jointly conducted by Mr Wong and Mr Cheung on 21 March 2022:

(i) Greenish-dyed water from the bathroom of the 3/F Unit was found in the ceiling of Room C near the door and the corridor in the 2/F Unit[8]. Mr Cheung commented that such seepage was caused by water leaking through the marble curb on the corridor of the 3/F Unit down to the 2/F Unit ceiling.[9]

(ii) The dye ponding test on 21 March 2022 also showed that greenish-dyed water seeped from the bathroom of the 3/F Unit to the floor of the living room in the 3/F Unit. Mr Wong suggested in court that this could be due to the wearing out of the L-shaped waterproof membrane between the wall and the floor in the bathroom. As there is no waterproof membrane for the floor slab in the living room, water then seeped downwards and dampened the ceiling of Room C.[10] The repairment of the marble slab at the door of the bathroom on 3/F would not eliminate this problem.

(iii) Mr Cheung agreed that measurements of moisture contents be carried out again to the affected areas on a second site visit on 23 March 2022. High moisture contents, ranging from 29.5% to 34.5% (well above the normal 17%), were recorded in those areas despite no colour stain was noted.[11]

75.  The 2^nd Defendant denies any leakage from the floor slabs. It appears from her evidence that any sources of leakage from the 3/F Unit were eliminated as a result of the repair works carried out by the 1^st Defendant in June 2022. It would therefore follow that the results of the tests, which were conducted before the said repair works, are irrelevant and do not assist the Plaintiffs’ case.

76.  The Plaintiffs also rely on the subsequent inspections of the JO and its consultants. On 23 December 2022, the JO conducted a drainage dyed water test in the 3/F Unit but was unable to identify the source of leakage. As the problem of leakage continued, the JO then engaged a consultant to inspect the 2/F and 3/F Units on 21 March and 18 April 2023 and recorded moisture contents between 35% and 80% in Room C. While the consultant was unable to identify the source of seepage, it ruled out drainage, water supply pipes and the external walls as possible sources.

77.  On 2 August 2023, Mr Wong conducted another inspection in the 2/F Unit and found that the ceiling of Room B was still sustaining water leakage with the source identified at the floor of the bathroom and kitchen of the 3/F Unit.

78.  In the joint inspection on 19 September 2023, Mr Wong and Mr Leung conducted, amongst others, dyed water ponding tests in the bathroom and kitchen of the 3/F Unit. Water with different colour dyes was poured on the floor, and in the toilet, shower and sink in the bathroom, as well as the floor, sink, and sewage pipe in the kitchen. The experts then checked if colour stains were observed in the 2/F Unit. Moisture contents in various parts of the 2/F Unit were also measured by way of infrared scanning and conductive moisture meter before and after the test on 19 September 2023, and again on 21 September 2023.

79.  According to Mr Leung:

(i) Infrared scanning showed that a large amount of water was trapped in the wall of Room C that is next to the external wall, as well as the wall of the Room B toilet that is also next to the external wall.[12]

(ii) However, with the use of a conductive moisture meter, he did not observe an overall change in the moisture contents (整體濕度沒有變化) in the ceilings and walls of Rooms B and C after the ponding tests.[13]

(iii) No colour stain was observed in any of the tested areas.[14]

(iv) He observed peeled paint, peeled plaster, hollowing, cracks, rusted water pipes and rusted steel bars in the external walls.[15]

(v) During the 10 days before 19 September 2023, the Hong Kong Observatory recorded 227.6mm of rain water, whereas there was no rain between 19 and 21 September 2023.[16]

80.  Based on these observations, Mr Leung concluded that there was no evidence to show that there was leakage from the 3/F Unit and he inferred that the water leakage problem in the 2/F Unit was related to the seepage of rain water through the external walls.[17]

81.  Mr Wong disagreed with Mr Leung. He took the view that because repair jobs had been done to the bathroom and kitchen of the 3/F Unit, it might have become more difficult for dyes to seep through the floor, and the fact that no coloured stain was observed in the 2/F Unit does not mean that there was no water leakage from the bathroom and kitchen of the 3/F Unit.[18]

82.  Having considered the data collected in the tests, it seems to me that Mr Leung’s conclusion is unreliable, as one of the premises, ie. that there was no overall change in the moisture contents in the ceiling and wall of Room C, is inconsistent with the data collected. In particular, contrary to Mr Leung’s statement, the measurements carried out after the ponding tests on 19 September 2023 revealed significant increases in moisture contents in the ceiling and wall of Room C.

83.  Out of the 24 points for measurements on the ceiling of Room C, 14 sustained an increase in moisture content by as much as 100%.

Point	Moisture content before test (%)	Moisture content after test (%)	Percentage increase
4	43.2	44.9	4%
6	24.7	49.4	100%
7	26.5	41.3	55.8%
9	59.7	69.7	16.7%
10	33.6	79.7	137%
11	54.6	86.8	58.9%
12	27.9	58.4	100%
14	29.4	30.1	2.4%
15	22.1	35.8	61.9%
17	24.7	38.7	56%
19	20.3	22.5	10.8%
20	18.7	20.7	10.7%
21	19.3	21.4	10.9%
23	18.9	20.6	9%

84.  Similarly, 12 points on the wall in Room C facing the room’s door were marked for measurement and 3 of them noted significant increases in moisture contents of up to 300%.[19]

Point	Moisture content before test (%)	Moisture content after test (%)	Percentage increase
W1	18.6	74.6	300%
W2	41.8	99.9	139%
W3	58.5	99.9	70.7%

85.  Based on these measurements, I am unable to accept Mr Leung’s opinion that there was no overall change in the moisture contents in Room C. The data in fact show that there were significant increases in the moisture contents for many of the measurement points.

86.  There was no rain within the 2 hours of the ponding tests on 19 September 2023 and therefore water could not have leaked through the building’s external wall. In the section above, I have also ruled out the suggestion of fresh water pipes as a source of leakage. In any event, even if there was any leakage in the water pipes, the condition would have been continuous in the background and there should have been no significant change during the 2 hours. Thus, the only variable during the 2 hours was the ponding tests and the only possible cause that led to the increases in the moisture contents was the water that was poured onto the floors and the sinks of the toilet and kitchen of the 3/F Unit.

87.  Mr Leung has observed in his report that the silicon seal in the bathroom of the 3/F Unit was worn out and the tiles on the bathroom wall were peeling off.[20] He gave evidence in court that due to these conditions, water could seep into the floor slab and, if the waterproof membrane in the floor slab was defective, water could seep downwards to the lower premises.

88.  In this connection, I note that defective waterproof facility in the floor slab of the bathroom and kitchen was previously identified by the JO as the cause of water leakage from the 3/F Unit.[21] In the Nuisance Abatement Notice issued by the JO on 23 September 2021, the 1^st Defendant was ordered to rectify the defective floor slab in the bathroom and kitchen of the 3/F Unit within 42 days.[22]

89.  Whilst it is the 2^nd Defendant’s evidence that the 1^st Defendant had carried out certain repair works in June 2022 respectively, there is no evidence that such repair works involved repairing the waterproof facility in the floor slab and were sufficient to rectify the leakage. In fact, during cross-examination, Mr Leung accepted that if the waterproof membrane of the bathroom had been replaced or repaired, new silicon seal would have been applied; and since the silicon seal was worn out, it was unlikely that the waterproof membrane of the kitchen and bathroom had been redone before his inspection on 19 September 2023. In view of the increases in the moisture contents on the ceiling and wall of Room C immediately after the dyed water ponding tests, it is highly probable that the waterproof facility in the floor slab of the kitchen and bathroom of the 3/F Unit was still defective.

90.  The 2^nd Defendant relies heavily on the fact that no coloured stain was observed in the dyed water ponding tests and therefore the result was “negative”, suggesting that there was no leakage. However, it is well-known that the dyed water ponding test is not always successful. The lack of visible fluorescent dye is not in itself conclusive or detrimental to a plaintiff’s claim, and the court will look at all the available evidence before reaching a conclusion: Rich Target Properties Ltd v Treasure Ring Ltd [2025] 3 HKLRD 344 at §§81-86. That said, negative results of tests carried out by independent authorities should not be rejected in the absence of evidence suggesting that the tests were not properly done: Wu Hucheng v Tian Jiong & Another [2024] HKDC 1902 at §48.

91.  According to the Professional Guide to Water Seepage (“Professional Guide”) issued by the Hong Kong Institute of Surveyors in 2014, while a positive test result confirmed by the laboratory is firm proof of the source, a failure to record the presence of dye in the damp zone cannot be taken as definite evidence against the suspected source, as there are limitations to the test: see pp. 23-24.

92.  Mr Wong opined that two of the limitations stated in the Professional Guide, namely “surface decontamination and cleaning required” and “sensitive to micro-cracks > 1mm width” could be the reasons for the negative test results on 19 September 2023. Mr Leung disagreed in cross-examination, but he did not give any reasons. Given that some repair works were carried out in June 2022 which could have affected the penetration of dyes and there are possible limitations to the dyed water ponding tests, I accept Ms Chong’s submission that the lack of coloured stain observed in the 2/F Unit is just an inconclusive result, and it does not negate the fact that there were significant increases in the moisture contents in the ceiling and wall of Room C immediately after the ponding tests.

93.  The consultant engaged by the JO had also conducted dyed water ponding tests on 21 March 2023 but it was unable to identify the source of water leakage. Having studied the data and methodology, it is observed that there are at least two differences in the dyed water ponding tests conducted by the consultant as compared to those by Mr Wong and Mr Leung. First, the consultant only assigned 8 check points on the ceiling and wall of Room C, whereas there were 36 check points in the latter tests which rendered the coverage more comprehensive. The second and, in my view more significant, difference is that the consultant only waited for about 1 hour and 10 minutes before taking the second moisture content measurements, whereas Mr Wong and Mr Leung waited for 2 hours. If there were any defects in the waterproof facility in the 3/F Unit, a longer time period would naturally allow more water to seep through the floor slab and larger increases in the moisture content would be observed. This may explain why in the consultant’s tests on 21 March 2023, only 3 out of the 8 check points showed a small increase in moisture content.[23] It was under these circumstances, together with the fact that no coloured stain was observed in the 2/F Unit, that the consultant concluded that the source of leakage was uncertain. By contrast, the moisture content measurement results in the joint inspection of Mr Wong and Mr Leung are a lot more clear-cut and indicative of leakage from the 3/F Unit.

94.  Therefore, having considered all the test results conducted by the JO and the experts in this case, I am satisfied that, on the balance of probabilities, there was water leakage from the floor slab of the bathroom and kitchen of the 3/F Unit to the 2/F Unit as of 19 September 2023.

External wall

95.  The 2^nd Defendant’s case is that any water leakage in the 2/F Unit likely originated from the external walls of the building. She relies on the opinion of Mr Leung which in turn was based on (1) his visual inspection of the cracks in the external walls and (2) no coloured stain was observed from the dyed water ponding tests performed on 19 September 2023.

96.  The Plaintiffs seek to rebut Mr Leung’s visual inspection by Mr Wong’s spray test on the external walls, which purported to show that the moisture contents in the affected areas of the 2/F Unit had no significant change after the external walls were sprayed with water for 30 minutes.

97.  As mentioned above, I am not satisfied that visual inspection alone is sufficient to lead to any reliable suggestion (let alone conclusion) that the cracks in the external walls were a cause of the water leakage. I do not need to repeat my reason here.

98.  As for the spray test, I have also made my comments above that the methodology was unsatisfactory, as there was no floor plan reference whatsoever. It is simply impossible to know which parts of the external walls were sprayed and the corresponding areas within the 2/F Unit.

99.  With regard to the dyed water ponding tests, I have accepted the fact that there are limitations to the test and the absence of any coloured stain in the joint inspection on 19 September 2023 was inconclusive.

100.  In addition to Mr Leung’s opinion, the 2^nd Defendant also relies on the her communications with Madam Liu to show that the external walls were a source of leakage. The 2^nd Defendant sent a WhatsApp message to Madam Liu on 26 June 2023 informing the latter that certain repair works had been done to the 3/F Unit in about April 2023. Madam Liu replied on 18 August 2023 that the water leakage situation in the 2/F Unit did not improve. Mr Poon argued that, therefore, such repair works done to the 3/F Unit were wholly unrelated to the moisture condition in the 2/F Unit and the leakage must have originated from the external walls.

101.  I am unable to accept this argument. It is premised on the assumption that the repair works carried out in April 2023 (if any) were effective to eliminate any source of leakage from the 3/F Unit. There is no such evidence in court. In fact, as far as the court understands, such repair works were not directed at the 2/F Unit. Instead, they were carried out in response to a separate complaint that the 3/F fresh water pipes were leaking to the 1/F podium. Moreover, even if the repair works were unrelated to the moisture condition in the 2/F Unit, it does not automatically follow that the leakage must have originated from the external walls.

102.  In my view, the more reliable evidence on this issue is the inspection reports provided by the JO, which have excluded building’s envelope (ie. the external walls) as a source of water leakage. It is also Madam Liu’s firm evidence that no repair to the building’s external walls had been carried out between 2017 and 2024. Such evidence is not challenged by the 2^nd Defendant. If water had leaked from the building’s external walls and in the absence of any repair, the water leakage in the 2/F Unit would not have stopped when Mr Wong went to check the premises in around April 2024.

103.  For all the above reasons, I do not accept the 2^nd Defendant’s case that any water leakage in the 2/F Unit likely originated from the external walls.

Issue (3) Was there any continued water leakage for which the 2^nd Defendant is liable

104.  Where the source of water leakage is determined to have originated from the defendant’s property, it does not automatically follow that he is inevitably liable. To found liability in nuisance, the defendant must be shown to have actual or constructive knowledge that the water leakage originated from his premises. Knowledge means that the defendant actually knew, or what the defendant should have known with normal and reasonable diligence. The defendant with such knowledge will be found liable if no remedial action is taken to purge the water leakage without reasonable delay: Wu Hucheng (supra) at §50; Loke Yuen Jean Tak Alice (supra) at §55; Larbons Limited v Kuo You Weaving Factory Ltd, DCCJ 934/2006, 12 July 2007 at §76.

105.  Thus, a defendant who does not have actual or constructive knowledge that the water leakage emanates from his property is not liable. However, once the defendant has the requisite actual or constructive knowledge, he will be liable unless remedial action is taken without delay: Leung Wai Kee v Tam Yuen Sheng, DCCJ 5716/2007, 10 July 2012 at §43; Tin Kin Ka Clara v Chan Koon Cheong & Another, DCCJ 3139/2012, 11 May 2015 at §§54-55.

106.  A claim in negligence would stand and fall with a claim in nuisance. The law on negligence and the law on nuisance coincide in the sense that where an owner knows or ought to know that the conduct or omission relating to his land will cause harm to his neighbour, he is under a duty to avoid and/or abate such harm. (Siu Kwok Keung Raymond v Yee Shia Yuen, DCCJ 2131/2012 , unreported, 31 October 2017 at §101.

107.  The question here is whether the 2^nd Defendant had actual or constructive knowledge that the water leakage originated from her premises.

108.  There is no dispute that when the 2^nd Defendant purchased the 3/F Unit, she knew the following:

(i) Before she purchased the 3/F Unit, she was told by the 1^st Defendant that there was water leakage from the 3/F Unit to the 2/F Unit and the Plaintiffs had commenced proceedings against the 1^st Defendant.

(ii) She was given to read the JO June 2022 Letter issued to the 1^st Defendant[24] where it was stated, inter alia, that after the issuance of the Abatement of Nuisance Notice, the JO had inspected the 3/F Unit and found that renovation had been done but the 2/F Unit was still sustaining water leakage. The JO had arranged its consultant to conduct further inspection but was unable to identify the source of water leakage.

109.  The 2^nd Defendant said in court that she thought the repair works done by the 1^st Defendant were sufficient to rectify the water leakage from the 3/F Unit. She understood from the JO June 2022 Letter that the JO was unable to identify the source of leakage, and the leakage problem in the 2/F Unit was probably due to some source other than the 3/F Unit. Therefore, she decided to complete the purchase of the 3/F Unit.

110.  After she became the registered owner of the 3/F Unit, she arranged workers to test the water pressure of the pipes and repair the areas with concrete spalling within the unit, but she did not replace any pipes or waterproof membrane of the unit. She further said that she was all along willing to cooperate and assist the Plaintiffs to find out the source of leakage.

111.  On 11 December 2022, the 2^nd Defendant rented out the 3/F Unit. Shortly thereafter, in response to further complaints from Madam Liu, the JO on 23 December 2022 conducted drainage dyed water test in the 3/F unit. On 21 March 2023 and 18 April 2023, the consultant engaged by the JO carried out more tests in the 2/F and 3/F Units. The 2^nd Defendant thought that she was cooperative and willing to assist. She decided to wait for the JO’s inspection report before deciding what to do next, and she thought she was taking a reasonable, step-by-step approach (循序漸進) in dealing with the issue.

112.  Ms Chong for the Plaintiffs criticised the 2^nd Defendant for adopting a “cannot be bothered” attitude towards the water leakage problem. She argued that it was unreasonable for the 2^nd Defendant to wait for the report of the JO when the 2^nd Defendant as the registered owner had an independent duty to maintain her own property in good repair. Ms Chong pointed out that it was only when the 2^nd Defendant received the demand letter dated 3 May 2023 from the Plaintiffs’ solicitors, which was almost one year after she became the registered owner, that she started to contact the Plaintiffs and therefore there was an undue delay on her part to deal with the issue. Although it was not expressly stated in the submissions, the crux of the Plaintiffs’ argument appears to be that the 2^nd Defendant was fixed with the requisite constructive knowledge and she had the duty to investigate, locate and remove such leakage in a prompt and reasonable manner: Yan Wing Fai Rick v Century One Ltd, DCCJ 2773/2009, 2 February 2011 at §§84-85.

113.  The problem with the Plaintiffs’ argument is that it confuses “knowledge of source of leakage” with “knowledge of leakage”. While the former attracts liability, the latter does not: 張秀玲、吳炳漢 v 鄭禮莊, CACV 268/1998, 9 April 1999 at §§7-8. In other words, it would be insufficient to establish liability if the 2^nd Defendant only has actual or constructive knowledge that the Plaintiffs’ property is sustaining water leakage, but she has no actual or constructive knowledge that the water leakage originated from her premises.

114.  Here, there is no evidence to show that when the 2^nd Defendant became the registered owner, she had actual or constructive knowledge that the water leakage in the 2/F Unit originated from the 3/F Unit. Ms Chong relied on the JO June 2022 Letter, but that letter said nothing about the 3/F Unit being a possible source of leakage. On the contrary, it expressly stated that the JO was unable to identify the source despite it had engaged a consultant company to conduct further inspections; and since it had already carried out feasible and different non-intrusive tests, it could only suspend the case in accordance with the established procedures.[25] Given that the JO, being an independent public authority specialised in handling water leakage cases, had already investigated the matter with various tests and inspections and yet it was still unable to identify the source of leakage, one might reasonably question what additional benefit could be gained from engaging professionals to perform the same or similar tests. In these circumstances, it was not unreasonable for the 2^nd Defendant to rely on such investigation results and adopt a “wait and see” approach for the time being.

115.  Ms Chong also referred to the penultimate paragraph of the JO June 2022 Letter and argued that the JO had reminded the 1^st Defendant (being the registered owner at the time) of his independent duty to maintain his premises in proper repair and he was urged to cooperate with other flat owners and to engage professionals to resolve the water leakage problem. As such, she argued, the 2^nd Defendant had the duty to do the same when she became the registered owner of the 3/F Unit.

116.  I am unable to accept such an interpretation. The same paragraph was also found in the JO’s letter to Madam Liu on the same date.[26] On proper reading, it seems to me that the paragraph was not directed only at the 1^st Defendant. Rather, it served as a general reminder that owners are responsible for maintaining their properties and, in addition to seeking the JO’s assistance, owners could also resolve water leakage problems through cooperation and engaging professionals. There is nothing in the paragraph that imposed a duty on the registered owner of the 3/F Unit to specifically investigate the source of leakage.

117.  In short, I do not think there is anything in the JO June 2022 Letter that put the 2^nd Defendant on inquiry as to the source of leakage.

118.  Moreover, there is no suggestion that the 2^nd Defendant would have found that her property was a source of leakage had she exercised normal and reasonable diligence. In fact, there is evidence to the contrary. As mentioned above, in response to further complaints from Madam Liu, on 23 December 2022 the JO sent its staff to the 3/F Unit to carry out a dyed water test to the drainage but was unable to identify the source of leakage.[27] The JO then engaged a consultant to conduct further tests and investigations at the 2/F and 3/F Units on 21 March 2023 and 18 April 2023, including dyed water ponding tests and spraying tests. The consultant concluded that the source of leakage was uncertain, though it ruled out the drainage, water supply pipes and rain water seepage from the building envelope as possible sources of leakage.[28] Therefore, even the JO and its consultants were again unable to identify the source of leakage, and I do not think one can safely say that the 2^nd Defendant could have discovered the source with reasonable diligence.

119.  Moreover, at all material times since she became the registered owner of the 3/F Unit, the 2^nd Defendant has been cooperative and willing to assist the Plaintiffs in identifying the source of leakage. There has not been a single incident in which the Plaintiffs’ experts or the JO’s staff / consultants were denied access to the 3/F Unit.

120.  The 2^nd Defendant also appeared to be responsive to the Plaintiffs’ demand. Shortly after she received the demand letter dated 3 May 2023 from the Plaintiffs’ solicitors, the 2^nd Defendant on 10 May 2023 made an inquiry with Hong Kong Survey Limited to assist in identifying the source of leakage. On the same day, she also issued a reply to the Plaintiffs’ solicitors stating that: (1) when she purchased the 3/F Unit, the 1^st Defendant had told her that he had already fixed the water leakage issue; (2) based on her record, the 3/F Unit was vacant from February to November 2022 and the main water switch and power supply had been turned off and therefore she wondered where the leakage came from; and (3) she also wanted to clarify the problem and she was waiting for the test report from the JO to see what to do next.[29]

121.  On the other hand, even on the Plaintiffs’ pleading and evidence, Madam Liu had only complained to the 2^nd Defendant on two occasions in March and August 2023 about water leakage from the 3/F Unit to the 2/F Unit.[30] But by March and April 2023, the JO had already conducted another round of tests and still the source of leakage could not be identified. It cannot be said that the 2^nd Defendant had failed to respond to Madam Liu’s complaints.

122.  On 26 June 2023, the 2^nd Defendant through WhatsApp sent a message to Madam Liu informing the latter, inter alia, that in around April 2023, she had completed a small repair project in the 3/F Unit to fix a fresh water pipe that was previously leaking to the external wall on the 1/F podium, and that project had duly resolved the matter.[31] The 2^nd Defendant then asked Madam Liu to see if there was also improvement to the leakage problem in the 2/F Unit. But Madam Liu did not provide any immediate response.

123.  On 2 August 2023, Mr Wong inspected the 2/F Unit and commented that the property was still sustaining water leakage with the source identified at the floor of bathroom and kitchen of 3/F.[32] But there is no evidence that such a report was given to the 2^nd Defendant. It was only on 18 August 2023 that Madam Liu replied to the 2^nd Defendant on WhatsApp, saying that the moisture condition on the ceiling of the 2/F Unit did not improve. A joint inspection by Mr Wong and Mr Leung was then arranged to take place on 19 and 21 September 2023, and Mr Leung took the view that the source of leakage was likely from the building’s external walls. It appears from the above chronology that the 2^nd Defendant was responsive and there was no undue delay on the part of the 2^nd Defendant in handling the leakage problem.

124.  Ms Chong further argued that since the water leakage problem eventually desisted in around April 2024 (as per Madam Liu’s oral evidence) and there was no repair to the building’s external walls during the relevant period, the reasonable inference would be that the 2^nd Defendant eventually carried out repair works to her flat. She argued that had the 2^nd Defendant taken prompt action after she became the registered owner, the water leakage would not have persisted for 28 months from 29 July 2022 to April 2024.

125.  But this argument is founded on the premise that the 2^nd Defendant all along knew or ought to have known that her property was a source of leakage. As discussed above, there is no such evidence. Moreover, the 2^nd Defendant categorically denies to have conducted any repair works after April 2023. Madam Liu also accepted in cross-examination that the 2^nd Defendant had only contacted her once in April 2023 in respect of the repairs done to the 3/F Unit.

126.  Ms Chong referred to the joint report of 21 June 2024 where Mr Wong stated that at the inspection of 4 March 2024, some “remedial work” had been made to the leaking fresh water pipe in the wall of the kitchen of the 3/F Unit after his last survey in September 2023.[33] However, such a comment was refuted by Mr Leung who said that the 2^nd Defendant had clearly stated that no repair was done between the two joint inspections.[34] Mr Wong’s oral evidence in this regard is ambiguous. At one point he said that a man (whom he guessed to be the 1^st Defendant) and a lady told him on 4 March 2024 that there were repairs after his last visit in September 2023, but it is unclear why the 1^st Defendant was there in the first place. Mr Wong also referred to photos which purported to show new silicon seal having been applied in the kitchen and the bathroom to prove that repair works had been done,[35] but those photos were taken in 2022. Later in cross-examination, Mr Wong admitted that he might have mixed up the date with those of the joint inspections in September 2023. In summary, I do not think there is any reliable evidence to show, one way or the other, whether the 2^nd Defendant had carried out repair works after the joint inspection in September 2023.

127.  In any event, even if the 2^nd Defendant did repair her property again which eventually led to the stoppage of water leakage in April 2024, that of itself is not evidence that the 2^nd Defendant had all along been aware of her flat being a source of leakage and she procrastinated on the problem.

128.  In conclusion, I am not persuaded that that the 2^nd Defendant had actual or constructive knowledge that water leakage originated from her property. Therefore, she is not liable for the continued water leakage after she became the registered owner of the 3/F Unit.

Issue (4) Quantum of damages

129.  Since I have held that the 2^nd Defendant is not liable, it is unnecessarily for this court to consider the issue of damages. However, in the event that I am wrong and the 2^nd Defendant is liable, I would assess the Plaintiffs’ entitlement to damages as follows.

130.  The Plaintiffs have reached settlement with the 1^st Defendant under which the Plaintiffs were paid HK$220,000. According to Ms Chong, the sum was calculated to represent roughly the Plaintiffs’ loss of rental for 62 months from 1 June 2017 to 29 July 2022.

131.  Now the Plaintiffs claims against the 2^nd Defendant damages comprising the cost of reinstatement, loss of rental for Room C from August 2022 to August 2025 (up to this trial) and damages for distress and discomfort:

Cost of reinstatement	HK$63,000
Loss of rental ($3,300 x 36 months)	HK$118,800
Distress and discomfort	HK$50,000

132.  The Plaintiffs rely on Mr Wong’s estimate to support their claim of HK$63,000 for cost of reinstatement. Mr Poon argued that this sum is excessive, as quotations obtained by the Plaintiffs from two contractors were only HK$22,500 and HK$27,500. I agree that the amount of HK$63,000 is excessive and I would adopt the sum of HK$22,500.

133.  As for why the Plaintiffs are claiming loss of rental up to the trial despite that there was no more leakage since around April 2024, Ms Chong told the court that the Plaintiffs were in lack of funds and they wanted to preserve evidence for the trial. I cannot accept such an explanation. The amount involved for reinstatement is not substantial and it is unclear what evidence was required to be preserved. In my view, the Plaintiffs ought to have mitigated their loss by commencing reinstatement works as soon as they were told that there was no longer any leakage. Thus, I would only allow their claim for loss of rental from August 2022 up to and including June 2024 (allowing two month for the reinstatement works to be completed and letting out the property), ie. 23 months.

134.  With regard to distress and discomfort, in the recent case of Yeung Yi Lan v The Incorporated Owners of Kam Shing Building [2024] HKDC 2140 at §§72-81, the court observed that in most of the cases cited to the court, the awards of damages for stress and inconvenience were to plaintiffs who resided at the property in question and therefore they personally experienced or endured the discomfort from water leakage. In that case, however, the plaintiff was a landlord who did not occupy the property. In the absence of authorities before the court which were directly on point, the court held that the owner could not in principle claim damages for stress and discomfort under the tort of nuisance. However, since the defendant acted in breach of an express provision of the deed of mutual covenant, the court held that the plaintiff was nonetheless able to recover general damages for breach of contract in the sum of HK$50,000.

135.  I do not think the case of Yeung Yi Lan assists the Plaintiffs here, as a breach of the deed of mutual covenant is not pleaded in their Amended Statement of Claim. In the absence of any authority before me that landlords can claim damages for distress and discomfort under nuisance, I would not be minded to allow this head of damages.

136.  Therefore, if the 2^nd Defendant is held to be liable, the Plaintiffs would be entitled to damages in the sum of:

HK$22,500 + HK$3,300 x 23 = HK$98,400

Conclusion

137.  The Plaintiff’s claim is dismissed. I make an order nisi that the 2^nd Defendant shall have the costs of these proceedings to be paid by the Plaintiffs, with certificate for counsel, to be taxed if not agreed. This order nisi shall become absolute unless an application to vary is made within 14 days from the date of this decision.

138.  I thank counsel for their assistance provided to the court.