Joint Office Can't Find the Leak Source? What to Do Next in Hong Kong

Water is coming through the ceiling or a wall, and the first instinct for most people is to report it to the Joint Office for Investigation of Water Seepage — it's the official channel, so surely its finding should carry the most weight. But in practice, plenty of cases wait months only to get back "source not conclusively identified." At that point, many people assume the matter is simply over — the upstairs owner still won't admit fault, and the repair costs and losses sit with them.

That's not actually the end of the road. This guide draws on public materials from the Joint Office for Investigation of Water Seepage, a government press release, CLIC (the Community Legal Information Centre) and the Hong Kong Judiciary to explain what options remain once the Joint Office can't confirm a source, what standard of proof the Tribunal actually applies, and the traps that most often catch people before and after filing. If you'd like the general water-damage claim process first, see our complete guide to water-damage claims.

Joint Office Can't Find the Source — Is That the End of It?

First, how the Joint Office actually works. Per the government press release, the Joint Office's investigation runs in three stages, targeting 90 working days from case receipt to completion — Stage I contacts the complainant within 6 working days, Stage II runs to a cumulative 32 working days, and Stage III to a cumulative 52 working days. That sounds orderly, but actual on-time completion within 90 working days ran at only 70%, 68.5% and 65.4% for 2021, 2022 and 2023 respectively — meaning nearly a third of cases exceeded that target window.

Why does the Joint Office end up unable to identify a source?

Per the Joint Office's own materials, if Stage I and II investigations still haven't identified a source and the case is genuinely complex (multiple bathrooms, multiple seepage points, for instance), the Joint Office moves to Stage III — a professional investigation, engaging a consultant for more thorough testing. But even at that stage, if the result still doesn't identify a source, or if the seepage becomes minor, intermittent, or has visibly improved during the investigation, the Joint Office will discontinue its intervention. In other words, an "inconclusive" finding often isn't because the source truly cannot be determined — it's that the government investigation has a real stopping point; resources are finite and can't chase a case indefinitely.

It's also worth noting that where a case is found to involve a structural or drainage issue, the Joint Office refers it to the Buildings Department or another relevant department for follow-up — but the press release also states the Joint Office keeps no statistics on the completion rate or delay causes of referred cases, meaning there's no fixed answer to how far or how quickly a referral actually goes.

The Tribunal's Standard of Proof: You Don't Need an "Ironclad" Finding

This is where most of the misunderstanding sits — many people assume you need an official document stating definitively "it was this party" before filing makes any sense at all. That's not the case.

How solid does the evidence actually need to be for the Small Claims Tribunal?

Like other civil courts, the Small Claims Tribunal applies the civil standard of proof, not the criminal one. Per CLIC (the Community Legal Information Centre), the standard of proof in civil cases is the "balance of probabilities" — meaning the facts you assert need only be, relatively speaking, more likely than not to be true. That's a materially lower bar than the "beyond reasonable doubt" standard applied in criminal cases, and the civil burden of proof is correspondingly easier to discharge.

Applied to a water-seepage dispute, that means: you don't need a government-stamped conclusion saying definitively "it was them" before you can file a claim. An adjudicator will weigh whatever evidence you have — an independent surveyor's or plumber's assessment report, whether the timing of the seepage lines up with renovation or repair work upstairs, the trend in moisture readings over time — and decide which account is, on balance, more probable. That threshold is a different thing entirely from proving a case beyond doubt.

Source Not Identified — What Can You Do Yourself?

Since you don't need an "ironclad" finding, commissioning your own assessment is even more worth doing — a well-documented private report is often exactly what tips an adjudicator toward your side.

What makes a private leak-source test actually useful evidence?

Engage an independent surveyor or plumber to test on-site, and make sure the report clearly states: the testing method used (a moisture meter reading, a dye test, infrared thermal imaging), the date and results of the test, and the professional's own reasoned conclusion on the likely source. A bare statement of "I suspect it's coming from upstairs" with no supporting data carries far less weight.

Two more things are worth documenting in parallel: the timeline (when the upstairs unit was renovated, when the ceiling stain first appeared, and the gap between the two) and a record of moisture changes (an inexpensive moisture meter and regular dated photos work fine). Neither needs to be officially certified, but together with the assessment report they form a complete "balance of probabilities" evidence chain. For a fuller walkthrough of assembling and presenting evidence at a hearing, see our complete guide to preparing evidence.

Do You Have to Wait for the Joint Office Before Filing?

Another common misconception: that you must wait for the Joint Office's final result before going anywhere near the Tribunal.

Can you file at the Tribunal while the Joint Office investigation is still open?

Yes. The Food and Environmental Hygiene Department's own FAQ on water seepage explicitly states that, besides seeking help from government departments, a resident can also consider engaging building and legal advisors to demand the responsible party stop the seepage under the terms of the Deed of Mutual Covenant, and even pursue compensation — in other words, seeking government help and pursuing a civil claim are two genuinely independent tracks that can run in parallel; there is no rule that the government track must produce a result first.

The practical consideration: the Joint Office's own target is already 90 working days, and roughly a third of cases run over that. If your loss is already clear-cut — persistent ceiling seepage, furniture already showing mould — simply waiting indefinitely only delays both the repair and the recovery. You can keep cooperating with the Joint Office's investigation while independently commissioning an assessment and building your evidence at the same time, and once you judge the evidence is strong enough, file directly against the suspected responsible party at the Small Claims Tribunal, up to a ceiling of HK$75,000.

If the seepage source is in a common area (the roof, a shared drainpipe), the party you pursue is different — see our guide on claiming against the Owners' Corporation for a common-area leak. If you already hold home insurance, our guide on choosing between an insurance claim and a Tribunal claim covers how the two routes can work together.

Named the Wrong Defendant? What Happens After You've Already Filed

For a case where the source hasn't been conclusively identified, the biggest practical risk usually isn't "the evidence isn't strong enough" — it's naming the wrong defendant, and that's the part most people overlook.

You've filed, and now realise the liable party isn't who you named — is there any way to fix it?

Per the Hong Kong Judiciary, a claimant must verify the defendant's name and last known address on the claim form; if the documents can't be served on the defendant, the Tribunal will ask the claimant to provide a correct address at the hearing, and if service repeatedly fails, the Tribunal cannot take the claim any further. So when the source hasn't been 100% confirmed yet, getting the likely responsible party's correct identity and address right at the outset matters far more than most people assume.

If new evidence after filing shows liability actually lies with someone else (say, the true source turns out to be a different unit from the one first suspected), the Judiciary's own guidance is clear that this is fixable: a claimant who wishes to amend a claim must first obtain the adjudicator's written permission, then attend the registry in person to make the amendment and pay the prescribed fee — meaning an amendment is genuinely possible, but it isn't automatic; it requires actively applying and following through in person. The Judiciary also specifically advises claimants to verify their information as far as possible before filing, since every amendment costs extra time and money — getting it right early always beats fixing it later.

A Practical Timeline: From Waiting on the Joint Office to Filing

Putting all of this together, here's a reasonably practical approach for a water-seepage dispute where the source keeps failing to be confirmed:

• First 30–60 days after reporting: cooperate with the Joint Office's on-site testing, while starting to photograph and log moisture readings yourself
• While a complex case moves into Stage III professional investigation: don't just wait — commission your own independent surveyor or plumber for a private assessment and written report
• Once the Joint Office discontinues its investigation, or you feel it's taken too long: assemble your assessment report, timeline, moisture records and correspondence, and serve a claim form on the suspected responsible party — verifying their correct name and address before filing
• If new evidence emerges after filing: apply to the adjudicator for written permission to amend the claim — don't just wait and see

Keep in mind that although the Tribunal's standard is "balance of probabilities" rather than an ironclad finding, that doesn't mean evidence doesn't matter — an assessment report, a clear timeline and moisture records remain the foundation for persuading an adjudicator your account is the more probable one. If you'd like someone to walk the whole process with you, see what our filing assistance service actually covers, or browse more on how a water-leakage claim plays out in practice.