In standard water batteries (two-handle) leak, hence the seepage of water may be caused by damage to the valve seat. Pitting is formed as a result of cavitation. You can renovate such a battery by milling the socket with a special hand tool. A disk cutter is placed on the knob of such a device, which, after inserting the device into the battery socket, the socket surfaces are aligned like this, that there is no leakage after screwing in the valve head.