Toilet cistern keeps running or making noise

The cause is usually a worn or dirty inlet valve (float valve), which allows water to keep flowing. Remove the lid of the cistern and check whether the float is stuck or the valve is leaking. Often, cleaning or inexpensively replacing the valve seal is enough – spare parts are available at hardware stores. If water drips into the bowl without flushing, the outlet valve (flush seal) is usually faulty; this can also be replaced easily. If in doubt, turn off the water at the shut-off valve beneath the cistern until the replacement part is installed.