Putting food colour inside the flush tank is a simple technique to determine whether your tank is leaking or not. Use a spanner to release the bolt on the back side of the tank top to open the tank. Wear a set of gloves and sprinkle food colour inside the tank, use your hands to mix it with water so that it gives a dark colour. Do not flush the tank yet, just observe the fixture for any possible leakage.
If the coloured water drips in the commode bowl, it means that the tank‘s flapper valve needs to be replaced
Stop water supply to the tank and flush the pot. Now the flapper valve will be visible at the bottom of the tank, it’s usually black in colour. Take out the valve and take it to your nearby store to get the exact same model. Place the new valve inside the tank and seal it completely. Now repeat the food colouring process again to check whether the new valve is leaking or not.
Now it’s time to remove the ball cock, which is also known as the water inlet valve and is present on the shaft inside the flush tank. It goes down when the water level recedes, then rises back again when the tank is filled.
If the ball cock is working fine, the water level in the tank will be maintained at a specific level. However, if it fails to keep the water level in check, the water will keep on adding to the tank till the tank overflows.
After replacing the ball cock, also check the water supply line to make sure it is not leaking.