How to find silent toilet leaks in your rentals
If you pay the water bill, a running toilet is money down the drain every hour. Even if tenants pay, a leak that goes on for months can damage the floor around it.
The dye test
- Put ten drops of food coloring in the tank.
- Put the lid back on and don't flush.
- Wait twenty minutes.
- If colored water shows up in the bowl, the toilet is leaking.
Do it at every turnover, and give tenants the same steps so they can check on their own.
The usual fix
Most leaks come from the flapper, the rubber seal at the bottom of the tank. Flappers often last about five years. To replace one, turn off the valve behind the toilet, flush to empty the tank and fit the new flapper with the chain set to the right length.
Check the supply valve too
Repair or replace the valve behind the toilet if it leaks or won't shut off. It's the one your tenant needs when a toilet overflows.
Teach it once, for every tenant. SaferResident sends each tenant a 20 minute phone course built around your building, with reminders, and gives you a certificate for every unit. $2 per unit per month, billed once a year as $24 per unit. Free for the first 60 days.
Sources
- How to catch a running toilet, Portland Water Bureau, City of Portland, Oregon
- How to Prevent Interior Water Damage from Plumbing and Appliances, Insurance Institute for Business and Home Safety (IBHS)
Updated October 1, 2026. General safety information. It doesn't replace your building's safety systems, local codes or your lease. In an emergency, call 911.