In any water Supply system, Water that produced and released to  the distribution system does not fully generate revenue for the Water Authority. This   is mainly due to the loss of water through the distribution system by leaks. The quantity of water that does not produce any revenue is usually turmed as Non Revenue Water (NRW).  This is usually expressed as percentage of water supplied to the system. While NRW is a threat to the financial sustainability of Water authority is commonly used as a KPI in Water Authority.