Guide: toilets
Diagnosing a Running Toilet Step by Step
A running toilet wastes water and money. Most causes are simple. Here is how to find which part is failing.
- Written by people who do the work
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- Steps you can safely do yourself
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Lift the lid and look
Take off the tank lid and watch a full flush. The flapper lifts, water drains into the bowl, the flapper closes, and the fill valve refills the tank until the float shuts it off.
Common causes
- Flapper not sealing. tired, bent flappers leak a trickle into the bowl. Try a colour test: tint the tank water and check the bowl after a quarter hour.
- Chain too short or tangled. The flapper cannot close fully. Adjust so there is a little slack.
- Water level too high. Water flows into the overflow tube. Adjust the float so water settles roughly 2.5 centimetres under the rim of the overflow.
- Fill valve failing. It keeps running or hisses. Replace the fill valve.
- Flush valve seal cracked. Less common, but requires removing the tank to fix.
Close the small valve at the wall behind the toilet while you work. It saves water and makes adjustments easier.
Time to phone us
If you have replaced the flapper and adjusted the float and it still runs, or if water leaks at the base or between the tank and bowl, call. Older toilets may need specialized parts or replacement. See toilet repair and toilet installation.
Check your water bill
A running toilet can raise a water bill significantly. Our water bill guide explains how to spot a hidden leak.