Some of the most expensive leaks in a home make no noise at all. A toilet can trickle into the bowl all day and night without a sound. A drip under the floor can run for months before you see a damp patch.
You don't need a plumber to find out if it's happening. You need your water meter, some food coloring and a couple of hours.
Test 1. The meter test (1 to 2 hours)
- Turn off every faucet. Make sure nobody uses water during the test: no washing machine, no dishwasher.
- Find your water meter and take a photo of the reading.
- Wait 1 to 2 hours without using any water.
- Read the meter again.
If the numbers have moved, water is escaping somewhere. Many meters also have a tiny leak indicator, a small dial or triangle that spins when water flows. Check the toilets first, because they're the most common hidden leak.
Test 2. The toilet dye test (15 minutes)
- Lift the lid off the toilet tank and set it somewhere safe. It's heavy and breaks easily.
- Take out any cleaning block, then add a few drops of food coloring to the tank water.
- Wait 15 minutes without flushing.
- Look in the bowl. If colored water has appeared, the tank is leaking into the bowl.
The usual culprit is a worn flapper, the rubber seal at the bottom of the tank. It's cheap and easy to replace yourself.
While you're at it: that dripping faucet
A faucet dripping once a second can waste more than 3,000 gallons (11,000 liters) a year, according to the US EPA's WaterSense program. If it's the hot faucet, you're paying to heat that water too. Most drips come from a worn washer or cartridge, a simple fix once you know how.
When to call a pro
If the meter keeps moving and you can't find the leak, or you spot damp patches on floors, walls or ceilings, call a plumber. Hidden leaks cause mold and damage. Renters: tell your landlord in writing straight away.
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