How to Fix a Running Toilet
That constant trickling sound wastes water and money. Nine times out of ten it's a cheap part you can fix in 15 minutes, with no plumber.
Lift the tank lid and look
A running toilet almost always has one of two problems inside the tank: the flapper (the rubber seal at the bottom) is leaking, so water keeps trickling into the bowl, or the water level is set too high, so water spills down the overflow tube in the middle. Both are easy, cheap fixes.
FIXTry these in order
No tools needed for the first three.
Flush, then look inside. The chain from the handle to the flapper should have a little slack, about the width of a finger. Too tight and the flapper can't close; too loose and it can get caught underneath. Adjust it by moving the clip to a different link.
The overflow tube is the open pipe in the middle of the tank. If water is spilling into it, the water level is too high.
- Float cup (a cylinder on the fill valve): squeeze the clip on its rod, or turn the adjustment screw, to lower it about 1 cm.
- Float ball (a ball on an arm): turn the screw on top of the valve, or gently bend the arm down.
The water should stop about 2–3 cm (an inch) below the top of the tube, or at the fill line marked inside the tank.
Put 10 drops of food colouring in the tank, don't flush, and wait 15 minutes. If colour appears in the bowl, the flapper is leaking.
Clean the flapper and the ring it sits on with a cloth to remove grime and mineral build-up; sometimes that's enough.
- Turn off the water at the valve behind the toilet (turn it clockwise), then flush to empty the tank.
- Unhook the old flapper from the pegs on the overflow tube and the chain. Take it to a hardware store to match the size (usually 2 or 3 inches).
- Fit the new one, attach the chain with a little slack, turn the water back on and test.
A new flapper costs a few dollars and is the most common fix.
If water keeps hissing into the tank even when the level is right, the fill valve (the tall part on the left that refills the tank) is worn. Universal replacement kits include instructions and take about half an hour. Turn off the water and empty the tank first, and keep a towel handy for the last bit of water.
If water is leaking at the base or from the tank bolts, or the valve behind the toilet won't turn off, call a plumber.
FAQCommon questions
How much water does a running toilet waste?
A lot. A constantly running toilet can waste hundreds of gallons a day, which shows up on your water bill.
My toilet refills by itself every so often. Why?
That's a “phantom flush”: a slow flapper leak lets the level drop until the fill valve tops it up. Replace the flapper.
Which flapper do I need?
Most are 2 or 3 inches. Take the old one to the store, or check the toilet's model number inside the tank.
Do I need a plumber?
Usually not for a running toilet. Call one for leaks at the base, cracks in the tank or bowl, or a stuck shut-off valve.