Hidden water leak detection

Check your water meter first

• Turn off every tap and any appliance that uses water.
• Make sure nothing is filling, such as a toilet tank or a humidifier.
• Write down the meter reading and wait a while without using water.
• Read it again. If the number has moved, water is going somewhere.

Toilets are a common hidden cause, so check those next. Put a few drops of food colouring in the tank and see if colour reaches the bowl without a flush.

How we track it down

Water travels along pipes and framing before it shows, so the stain is often not under the leak. We start with where and when it appears, then use moisture detection and thermal imaging where they help, along with isolating parts of the plumbing to narrow it down. The aim is to open only what is needed.

Where hidden leaks tend to start

• Supply pipes inside walls and ceilings
• Drain lines under tubs and showers
• Fittings behind toilets and vanities
• Older pipe, including Kitec and other materials nearing the end of their life
• Connections at the water heater

Not every wet wall is a plumbing leak

Water in a basement wall can come from outside, from surface water, poor grading or downspouts draining too close to the house. If what we find is not a plumbing problem, we tell you that instead of selling you a repair. Water that comes up from the floor is a different question. See basement flood protection.

Leaks in condos

In a condo, the water on your ceiling may be coming from another unit or a shared pipe. Your building's management usually needs to be involved, and shut-offs may need notice. See condo plumbing.

Once we find it

We explain where the leak is and what fixing it involves before starting. See leak repair for the common repairs. If water is pouring out, shut off the main valve and call (416) 489-0000.