Video Source: Washing Machine Fill Valve

If your washing machine fills with water after there could be a couple of things causing it. The drain pipe might not be set up correctly, which is enabling water to run back into the machine, or the water inlet valve could be passing. In this video the water inlet valve is passing and will be replaced.

If you are not sure about the water inlet valve being faulty, you can simply isolate the valve to the washing machine, if it no longer fills with water- you know that the water inlet valve is faulty. It is useful doing this, if you have a machine with a hot and cold supply, as it is not always obvious which valve is faulty., by isolating one valve at a time, you can find out which one is passing!