Rainwater harvesting tank

A rainwater harvesting tank captures run-off from roofs and stores it for non-potable uses such as toilet flushing, washing machines and garden irrigation. Systems usually include a leaf and silt filter at the inlet, a calmed entry to reduce disturbance of sediment, a floating intake, a delivery pump and a top-up from mains water when storage runs low. UK installations follow BS 8515 and Building Regulations Part G and require dual pipework with permanent identification to prevent cross-connection with the drinking water supply. Tanks may be installed below or above ground and sized using rainfall data and predicted demand. Rainwater harvesting is increasingly used in Greater London new build projects to meet planning conditions on water efficiency and reduce surface water discharge to overloaded combined sewers.