How to Fix a Running Toilet

Written by
Robin S
Published on
November 25, 2025
Introduction
A running toilet is really annoying to deal with. It wastes hundreds of litres of water every day. This will cost you a lot of money on your utility bills. Fixing a running toilet is usually easy to do.
If your toilet does not stop running after you flush it or it keeps refilling all the time, there are a few basic tools you can use to fix the problem.
In this article, we will talk about how to fix a running toilet, what causes the problem, and when you should call a plumber to help you with your running toilet.
A running toilet usually has one of the following problems.
A running toilet will have problems like a flapper that does not shut correctly.
It can also be a fill valve that does not shut off correctly.
Sometimes the float has been set high.
There can be a misaligned flush valve.
Water leaks into the overflow tube.
All these problems with a running toilet cause water to constantly drain from the cistern and into the toilet bowl.
A running toilet usually has one of the following problems.
A running toilet will have problems like a flapper that does not shut correctly.
It can also be a fill valve that does not shut off correctly.
Sometimes the float has been set high.
There can be a misaligned flush valve.
Water leaks into the overflow tube.
All these problems with a running toilet cause water to constantly drain from the cistern and into the toilet bowl.
Before you start fixing anything, you need to do some things.
Find the isolation valve. It is usually at the back of the toilet.
You have to turn the isolation valve clockwise. This will shut off the water supply to the toilet.
Now flush the toilet. This will empty the water from the cistern in the tank.
Then use a sponge or a towel to soak up any water that's still in the toilet tank.
To start, you need to take the lid off the toilet cistern. Then you can take a look at the things. You will see a few parts.
* The toilet has a flapper or flush valve seal at the bottom.
* There is a fill valve or ballcock that helps control how much water gets into the cistern.
* The water level is connected to a float. This float can be a ball or a cylinder.
* In the middle, you will find an overflow tube.
Now look closely at all these parts to figure out where the water is leaking from. You have to check the toilet cistern mechanisms one by one to find the source of the leakage. The toilet cistern mechanisms are important to check.
Published: November 25, 2025
Updated: June 25, 2026
