This easy to fit mains water top-up kit will ensure you always have water even in dry spells. The kit contains a robust float switch (similar to those found on some of our submersible pumps) which can be secured at any height on the vertical inlet pipe. If the water falls below this point, the float switch will open an external solenoid valve to part fill the tank from the mains supply, allowing rainwater to fill the rest. To provide an air gap and comply with regulations, the tank is filled via a stainless steel tundish, which can be mounted anywhere on the rainwater inflow pipe.