If you discover that water is escaping or in some cases pouring out from an overflow pipe on your building, it will probably mean that it will be coming from a cistern that has a faulty float operated valve (ball valve) that has more than likely failed to close off its water supply. A Bethnal Green Plumber can fix faulty valves. Several causes of the valve malfunction are:1). The internal washer has worn out and finally perished over the passage of time.2). Lime scale, causing the internal components to tightly rub together, preventing the valve from the moving freely and closing. 3). The float (or ball) itself could have developed a leak and have filled with water, but this is quite rare, and if this is the case simply replace it. Bethnal Green Plumbers can carry out this type of work.Replacing the valve is quite a simple process: 1). Isolate the water supply.2). Lower the water level in your storage cistern if you have one by flushing the WC or opening a tap.3). Take out the old valve. It is possible to usually undo the large union nut in the cistern which will allows the valve to come away for servicing and inspection. The part left is that, which holds the valve in the cistern and onto which the water supply is connected. You can now simply undo this nut on the new valve. If no internal union is there, you will need to replace the whole valve.4). Fit the replacement valve. It is quite easy.5). Set the water level as required. This is indicated by a mark inside the WC cistern saying ‘water level’, or in the case of the storage cistern is nearly always 25mm below the point were it would overflow.