Homeowner guideTroubleshooting
Signs of a Hidden Water Leak at Home
Some leaks are obvious. Others hide behind walls or under floors for months. Watch for these signs.
Cozy kitchen interior featuring a rustic double sink, decorative brick wall, and vibrant backsplash.
- Short steps a homeowner can follow safely
- What to check before you pick up the phone
- Clear signs it is time to call a plumber
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The short version
- Stains on ceilings or walls.
- Peeling or bubbling paint.
- Warped or soft flooring.
- Mould or mildew spots.
- Water around toilets, tubs or appliances.
Other signs
- A musty smell in one area.
- Higher water bills.
- A faint rushing noise in the walls with every tap shut.
- Warm spots on floors.
- Cracks in a foundation with damp edges.
Where leaks hide
| Location | Common cause |
|---|---|
| Under sinks | Loose fittings, failing supply lines |
| Behind toilets | Supply lines, wax seal |
| Shower walls | Valve leaks, failed grout or caulk |
| Basement ceilings | Pinhole leaks in pipes |
| Around the water heater | Valves, fittings, tank failure |
From the van: Use the water meter test: record a reading, avoid using water for two hours, and read again. Any change suggests a leak.
Act early
Small leaks can cause big damage. Mould can grow within a day or two in wet areas. If you suspect a leak, turn off water to the affected fixture or the main, and call a plumber.
Check the obvious places monthly
Set a reminder to open every sink cabinet, look behind each toilet and glance at the water heater base once a month. It takes five minutes. Most of the hidden leaks we trace in Markham homes left small clues in exactly those spots weeks before anyone noticed a stain.
Keep a flashlight handy for this round; damp wood and mineral tracks are much easier to spot under direct light.