How to Fix a Running Toilet

Overview

A running toilet can waste hundreds of gallons of water per day. This guide covers diagnosing and fixing the most common causes.

Step-by-Step Fix

1. Locate the isolation valve, usually found on the pipe leading to the toilet at the back or underneath, and turn it clockwise until the water flow completely stops. This will prevent any further water entering the cistern while you work.
2. Carefully lift the ceramic lid off the toilet cistern and place it gently on a soft, flat surface like a towel on the floor, away from any risk of accidental breakage. Ceramic lids are heavy and fragile, so handle with both hands.
3. Examine the rubber flapper at the bottom of the cistern where the water drains into the bowl; if it appears bent, stiff, or has visible signs of wear and tear, replace it with a new, compatible flapper to ensure a proper seal.
4. Observe the water level inside the cistern: if it's too high and spilling into the overflow pipe, adjust the float mechanism downwards, either by bending the float arm slightly or by turning the adjustment screw on the fill valve until the water level sits about an inch below the top of the overflow pipe.
5. Check the chain that connects the flapper to the flush lever handle to ensure it isn't too tight or too loose; there should be approximately half an inch (around 1-2 cm) of slack in the chain when the flapper is closed, allowing it to seal properly.
6. Press the flush lever to empty the toilet bowl and allow the cistern to refill completely, then listen carefully to confirm that the sound of running water stops entirely once the cistern has filled to the correct level and the flapper has sealed.

Common Symptoms & Diagnostic Resolutions

Review the common error codes and operating symptoms below to quickly identify the root cause of the fault before ordering replacement parts.

Frequently Asked Questions