The Unit Above Me Is Leaking. How Do You Prove It?

When water comes through your ceiling in a block of flats, the question is never really where the leak is.

The question is whose leak it is, because that is the one that decides who pays. In a sectional title scheme that question has teeth. It can sit between you and your neighbour, between an owner and the body corporate, between a managing agent and an insurer.

Here is the useful part: it is answerable. Not by opinion, and not by whoever sounds most confident, but by evidence.

Why this is harder than a normal leak

To prove where water is coming from in a complex, you generally need access to more than one unit, permission to flood something and leave it, and the patience to test one thing at a time and rule it out before moving on.

A plumber called to the unit with the damage has access to that unit and a mandate to fix a pipe. If the water is coming from somewhere else, they often cannot see it, cannot test it, and cannot prove it.

So what usually happens instead is that somebody looks at the stain, looks at the floor plan, and forms a theory. The theory then gets treated as fact, because nobody has anything better, and money gets spent on it. Sometimes the theory is right.

What proof actually looks like

At a complex in Green Point, a swimming pool was suspected of leaking into the unit below it. That is a serious allegation in a scheme, because it points at common property and a large repair.

I dived the pool using scuba equipment and dye tested it from the inside: the window, the lights, the return connection, the weir, the glass rails, and the tiles around the pool. I could not find any sign of a leak on the inside of the pool at all.

What I did find was multiple places around the pool where significant gaps were visible, and dye testing showed water being absorbed into those gaps and cracks. So the pool structure was not leaking. Water was getting in around it.

That is a completely different repair, a completely different cost, and quite possibly a different party responsible. Nobody would have known without testing it properly.

Often it is not the unit everyone suspected

This is the pattern I see most, and it is worth understanding if you are the person being blamed.

At a building in Sea Point, water was dripping down into the unit below. I tested the upstairs unit and the one below it, running pressure tests on both the hot and cold 15mm feeds at a little over working pressure, individually and separately from the hot water cylinder. Both held pressure, showing no uncontrolled flow of water anywhere in the unit. I then verified that with thermal scans.

At a unit in Vredehoek, the investigation was specifically to determine whether water from that owner's bathroom was responsible for problems reported in the neighbouring unit. I pressure tested the entire fresh water system at working pressure. No loss. I tested the basin separately. Sound.

In both cases the honest answer was the same: the water is not coming from this unit's fresh water plumbing. That is a real result, and if you are the owner who has been accused, it is the most valuable thing you can have.

And sometimes it is, but not for the reason assumed

At a complex where water was leaking from one unit into the one below, I pressure tested both the hot and cold water reticulations and both held. So there was no burst pipe, which is what everyone expects to find.

The pressure testing did reveal something else though: a faulty toilet inlet valve and a faulty toilet isolation valve, both needing replacement. Not dramatic, not a burst, but a genuine and continuous escape of water.

At another unit, where water was dripping into the flat below, the pressure test was clean and a 14mm camera through the sink, bath and basin drainage showed no joint separation and no defective pipe. The actual answer was the silicone around the bath, perished and letting water out when the shower was used.

Neither of those would have been found by assuming a pipe had burst.

What the report gives you, and what it does not

It gives you facts. What was tested, what was ruled out, what leaked, photographed, with dye you can see.

It does not tell you who is legally liable. That depends on your scheme rules, your insurance, and whether the failure is in common property or in a section, and that is a decision for your trustees and your insurer. What the report does is take the argument off whose leak it is and put it onto what to do about it. In my experience that is where most of these disputes were stuck anyway.

What makes the job possible

If you are a trustee, a managing agent or an owner arranging this, these are the things that matter:

• Access to the units involved, ideally on the same day. This is the one that most often delays things.
• Time. A flood test may need to sit for up to 24 hours. That is the test working, not slow work.
• Someone who can authorise it, since testing sometimes means plugging a drain or leaving an area under water.
• What has already been tried. Previous repairs change the picture, and knowing what failed is useful information.