- Difficulty
- Easy
- Time
- 30 to 60 minutes
- Parts
- $15 – $45
- To hire out
- $150 – $300
A toilet that keeps running is the most common plumbing fault in a house, and one of the few worth doing yourself. There is no soldering, no cutting, and nothing behind a wall. The whole repair happens inside the tank, where the water is clean and the parts cost less than a takeaway.
It is also worth fixing quickly. A running toilet can waste several hundred litres a day. On a metered municipal supply that is money going down the drain, and on a well it is needless wear on the pump.
How to tell this is your problem
- Water runs continuously, or the tank refills every few minutes without anyone flushing
- A faint hiss or trickle from the bathroom when nothing is in use
- You have to jiggle the handle to make it stop
- The water level in the tank sits at or above the top of the overflow tube
Should you do this yourself?
Yes, for almost anyone. The two parts that fail - the flapper and the fill valve - are held in by hand-tight fittings and cost under $45 between them. If you can turn a tap and follow a diagram, this is within reach.
Stop and call someone if
- Water is coming from the base of the toilet rather than inside the tank. That is a wax seal or a cracked bowl, and it is a different, wetter job.
- The shut-off valve behind the toilet will not turn, or weeps when you try. Old valves seize, and forcing one turns a $20 repair into a flood.
- The tank or bowl is cracked. Porcelain cannot be patched, and a hairline crack under pressure fails suddenly.
What you need
Tools
- Adjustable wrench
For the fill valve lock nut under the tank. A basin wrench is easier in a tight cabinet, but not essential on a toilet.
- Sponge and bucket
The tank never empties completely. You will be sponging the last inch out.
- Old towels
Assume you will spill some. Everyone does.
Materials
- Flapper
Take the old one to the shop rather than guessing. Sizes vary between 2 inch and 3 inch, and a near-miss will not seal.
- Fill valve
Universal adjustable-height ones fit almost every modern tank. Only needed if the flapper is not the culprit.
Step by step
- 1
Work out which part has failed
Put a few drops of food colouring in the tank and leave it 20 minutes without flushing. If colour appears in the bowl, the flapper is leaking. If it does not, but the tank still refills, the fill valve is not shutting off. This one test saves you buying the wrong part.
- 2
Shut off the water and empty the tank
Turn the valve behind the toilet clockwise until it stops. Flush to drain the tank, then sponge out what remains. If the valve will not turn, stop - see the warnings above.
- 3
If it is the flapper
Unhook the chain from the flush lever and slide the flapper ears off the pegs either side of the overflow tube. The new one goes on the same way. Set the chain with about half an inch of slack: too tight and it holds the flapper open, too loose and the handle does nothing.
- 4
If it is the fill valve
Disconnect the supply line from underneath, undo the plastic lock nut holding the valve to the tank, and lift the old valve out. Fit the new one with its washer inside the tank, hand-tighten the nut underneath, then give it a quarter turn with the wrench. Plastic threads strip easily - do not lean on it.
- 5
Set the water level
Turn the water back on and let it fill. The level should sit about an inch below the top of the overflow tube. Most valves adjust with a clip or a screw on the float. If water is running into the overflow, the level is too high, and that alone can make a toilet run for ever.
- 6
Test it properly
Flush several times and watch the tank refill and stop. Then leave it an hour and come back. Slow leaks only show up with time, which is why the colouring test is worth repeating at the end.
Mistakes that cost money
- Buying a flapper by eye. Take the old one with you - a 2 inch flapper on a 3 inch seat leaks no matter how well you fit it.
- Over-tightening plastic nuts. They seal on a rubber washer, not by force, and cracking the fitting means a new valve and a wet floor.
- Ignoring a seized shut-off valve. If it does not turn easily, that is the actual job, and it needs a plumber.
- Leaving the chain slack enough to slip under the flapper, which holds it open and recreates the fault you just fixed.
When to call a professional
Call a plumber if water appears around the base of the toilet, if the shut-off valve is seized or weeping, if the porcelain is cracked, or if more than one fixture in the house is behaving strangely at once - that usually points at supply pressure or venting rather than the toilet.
Hiring a plumber
What Ontario requires, how to verify it, and what the work should cost.