Why does my toilet keep running? Causes and fixes

A toilet tank has two jobs. The flush valve and its rubber flapper hold water in the tank until you flush. The fill valve refills the tank and shuts off when the float rises to the set level. If the flapper leaks, the tank slowly empties, the float drops and the fill valve turns on again, which is the hiss or short refill you hear in the middle of the night. If the fill valve does not shut off, water rises until it pours down the overflow tube, and the toilet runs nonstop.

Why does my toilet keep running?

How do I find where my toilet is leaking?

1. Take the tank lid off and put it somewhere safe; they are heavy porcelain and crack easily.
2. Look at the water level. If it is running into the top of the overflow tube, the fill valve is the problem. The tank's normal water line is usually marked inside the tank.
3. If the level is below the overflow tube, do a dye test: add a few drops of food colouring to the tank and do not flush. The US Environmental Protection Agency's WaterSense program says colour in the bowl after about 10 minutes means the flapper is leaking. Flush afterwards so the dye does not stain.
4. For a second check, turn off the water at the valve behind the toilet, mark the water level in the tank with a pencil, and come back in 10 to 15 minutes. If the level has dropped, water is leaking past the flapper or flush valve.

A silent leak is worth fixing even if the noise does not bother you. WaterSense notes that a worn flapper can leak thousands of gallons, many thousands of litres, a year. In Newmarket and most York Region towns you pay for water by the cubic metre on your utility bill, so a running toilet shows up as a higher bill before anything else.

How do I fix a running toilet myself?

If the fill valve is the problem

Lower the float so the water stops about 2 to 3 cm (about an inch) below the top of the overflow tube. Most modern fill valves have a plastic screw or clip on the side for this. If the valve still hisses or does not shut off, debris or mineral buildup may be holding it open. Fluidmaster recommends flushing debris out of the valve cap, and replacing the fill valve if that does not work. Universal fill valves fit most toilets.

If the flapper is the problem

Turn off the water, flush to empty the tank, and wipe the seat under the flapper with a cloth to remove grit and mineral deposits. If the flapper is stiff, warped or slimy, replace it. Flappers come in 2-inch and 3-inch sizes, and some toilets use brand-specific seals, so take the old one to the store or check the model number stamped inside the tank. Set the chain with a little slack: too tight and the flapper cannot seal, too loose and it tangles underneath. If a new, correctly sized flapper still leaks, the flush valve seat is probably rough or pitted, and the flush valve itself needs replacing, which means taking the tank off the bowl.

One more cause: in-tank drop-in cleaning tablets with bleach or chlorine. Fluidmaster warns that they damage the rubber parts in the tank, and a flapper that keeps failing early is often the result.

When should I stop and call a plumber?

• The shut-off valve behind the toilet is stuck or starts dripping when you turn it. Older multi-turn valves can break when forced. Turn off the main water valve instead and book the repair.
• Water is on the floor at the base of the toilet, or the toilet rocks. The wax seal or the flange under it has failed, and water may be soaking the subfloor.
• The tank is cracked, or water leaks from the bolts between the tank and bowl.
• You have replaced the flapper and fill valve and it still runs. The flush valve or the tank may be the problem.

What does a toilet repair cost on Doyo?

On Doyo, Toilet Repair is $224.20, the full price with Doyo's fee included. It covers a licensed plumber with a Certificate of Qualification (306A), common parts such as a flapper, fill valve or wax seal, taking the old parts away, and testing before they leave. Doyo checks the plumber's 306A before they are offered plumbing work, and you pay when the job is done. If the plumber finds a cracked tank or a broken flange, the extra work needs your agreement: under Ontario's Consumer Protection Act a pro cannot charge more than 10% over an estimate without it, and on Doyo that agreement is made in writing in the order chat.