The help of a professional plumber is required if your toilet is filling continuously. Basically, a constantly running toilet occurs when water in the cistern is either coming in or exiting the cistern when it shouldn’t. The parts involved in this malfunction include the ball valve and/or the flush valve. When the ball valve is the cause this can be due to a few reasons. The washers within the valve may have become worn and no longer functioning. This may be the reason when your toilet is constantly filling. Other causes include the float, fill valve or overflow pipe. Contact 24 Hour Plumber if your toilet is filling continuously. We provide expert help to repair your toilet.