Master Leak Detection Expert Teaches You How to Identify Water Supply Pipe Leaks.(Commonly known as tap water pipes or hot and cold water supply pipe leaks.)
Drain pipe leaks, septic pipe leaks, rainwater pipe leaks, fire pipe leaks.RC floor leaks in bathrooms, common wall seepage, or ceiling slab leaks.
Don’t rush to call a plumber yet!Let a professional leak detection expert show you the correct DIY leak detection methods.
Why not call a plumber first?
Because we often encounter inexperienced plumbers.
The moment they see a leak, they immediately start breaking the wall with an electric chisel.
They may demolish an entire floor but still fail to locate the leak.
Or, when they see an RC slab leak in the bathroom ceiling, they insist the homeowner repipe the whole system.
The worst-case scenario is when they break down a large section of the RC floor, but still can’t find the leak.
Learn some DIY leak detection techniques for hot and cold water pipes!
Shut-off Water Supply Test
If water is dripping from the walls or ceiling, the bathroom on the upper floor and the leaking bathroom on the lower floor must stop using water, including showering, washing, and flushing the toilet for 1-2 days.
The moisture trapped in the concrete walls will slowly evaporate. If the leak stops after shutting off the water. It means the issue is either a drain pipe leak or poor waterproofing in the bathroom floor.
In that case, skip to the “Drain Pipe Leak Detection” section below.But what if it still keeps dripping? Let’s keep going…
Water Supply Leak Detection
If, after performing the shut-off water supply test, the bathroom floor is dry but water is still dripping from the walls or ceiling at the same rate,then it can be determined that the leak is coming from the hot or cold water supply pipes. (commonly known as cold and hot water supply pipes.)
Step 1: DIY Water Leak Detection
Use a flashlight to inspect all faucet joints within a 2-3 meter radius of the water seepage area on the wall.Remove the decorative cover of the faucet and shine the light on the faucet joint inside the wall.
If you see that the concrete inside the faucet joint is blackened, it means there is moisture.This indicates a possible leak due to a loosely fastened faucet joint. Since the faucet is embedded in the tiles, the leaked water does not flow outside the tiles.Instead, it seeps inside the tiles, where there are brick walls with many gaps.The water travels through the brick wall and leaks out only when it finds a crack.The water may travel a long distance within the wall and leak out from the back or the bottom of the wall.
Step 2: Fixing the Leak
Simply remove the faucet, rewrap the thread seal tape (Teflon tape), and tighten it back!If the decorative cover is stuck and cannot be removed, preventing you from seeing the faucet joint. You can simply rewrap all faucet joints with thread seal tape and tighten them securely.A roll of thread seal tape only costs about NT$10
This is why you should never hire an inexperienced plumber to detect leaks.You might end up demolishing an entire wall just because of a simple faucet joint leak!
If the leak persists even after replacing all the faucet joint seal tapes.Congratulations, you’ve won the jackpot… The hot or cold water supply pipes inside the wall are truly leaking! (Sweat… 😓)In this case, first, determine whether it’s the cold water pipe or the hot water pipe that’s leaking. How do you determine that? Let’s keep reading!
Hot Water Pipe Shut-off Test
Find your water heater and turn off its power (if it’s a storage heater) or gas supply (if it’s a gas water heater.)
On the water heater, you will see labels: “Cold Water In” and “Hot Water Out.” Most water heaters do not have a valve for the hot water outlet.
You only need to close the cold water inlet valve.Then, open all hot water faucets on each floor to drain the remaining hot water.
Wait for one to two days. If the leak stops, it means the hot water pipe is leaking.
But if the leak continues, then the cold water pipe is the one leaking!
Once you identify which pipe is leaking, leave the rest to a professional pipe injection repair technician!
With modern technology, wall demolition is no longer necessary. Special pipe injection sealing agents can stop leaks without repiping!(Of course, if you prefer to install new pipes, that’s a different story.)
PS: When restarting the water heater, wait until the hot water faucet flows normally without air bubbles before turning the power or gas back on to avoid dry burning.
Drain Pipe Leak Detection
If the bathroom does not leak when not in use but starts leaking after a shower, the issue is either a drain pipe leak or floor waterproofing failure.
During a shower, water seeps into the gaps in the cement and sand under the tiles, creating a water-absorbing layer that causes leaks in the RC floor below.
Why do raised bathrooms tend to absorb more water?To raise bathroom floors (for sewer pipe installation), construction workers often mix extra sand into the cement, making it more prone to retaining water.
Floor Waterproofing Leak Test
1.Seal the drain opening completely with silicone and a round plastic cover.
2.Flood the bathroom floor with a shallow layer of water (about 0.5 cm deep).
3.Wait for a few hours to see if the lower floor starts leaking.
If it leaks downstairs, the bathroom floor waterproofing is faulty.
At this point, buy hard transparent waterproof paint (costs a few hundred NTD per bottle).
Apply a layer of it over the bathroom floor tiles, extending 30 cm up the walls.
Pay extra attention to the corners and around the drain opening.
However, if no water leaks downstairs after this test. Congratulations, you’ve hit the jackpot—it might be a hidden drain pipe leak.But this situation is very rare.
If it does happen, don’t panic.No need to rush into breaking tiles and spending a fortune!Just call a professional leak repair technician.
(We sincerely recommend the Yarui Pipe Leak Repair Training Center! With decades of experience, we have professional leak repair technicians across Taiwan—even for septic pipe sealing!)
Advanced Drain Pipe Leak Detection (Special Cases)
In general, drain pipes rarely leak because they have no water pressure.
However, because of the lack of pressure, plumbers often apply PVC glue to only one side of the joint or skip it entirely on vertical drain pipes.
This could turn into a week or even a month of unnecessary work.
Yarui’s Answer: The key point is…Hiring a professional is expensive—every minute of their work is backed by years of expertise.
Some leaks are incredibly easy to fix—why use a sledgehammer to crack a nut?
With a little research, you could fix it yourself for just $10 worth of thread seal tape or a few hundred dollars of waterproof paint.
But if you call a leak repair technician, you’ll likely spend at least a few thousand dollars for the same NT$10 solution—or even tens of thousands (NTD)if travel is involved. Why trouble yourself?
If you can identify which pipe is leaking, the technician can provide a quote more easily and quickly.
This saves both you and the technician valuable time.Naturally, the repair cost will also be cheaper!
Yarui Pipe Leak Repair Training Center – Master Huang Zu-De
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