Filter Pits require a fall between the building and the top of the tank of at least 750mm depending on the distance of the pipe run between where the pipe enters the ground at the building and the tank. This system will enable the pipes to be connected directly into the wall of the tank which leaves the top of the tank free for other uses.
Importantly, it eliminates the need for a tank screen on top of the tank. This prevents contamination of the tank water via the tank screen and reduces the amount of sunlight entering the tank thus minimising the growth of algae and other bacteria.