AWWA JAW51660

This article describes two indicators that evaluate the energy consumption of awater supply system. The structure indicator describes how the spatial distribution of users and water sources influences energy consumption. It is defined as the minimal energy that is necessary to lift a cubic meter of water to users and to give it a pressure of 6 bar (88 psi), a typical water pressure at the tap. In turn, minimal energy can be calculated as the difference between the potential energy of the delivered water (for some unit of time) and the potential energy of the same quantity of water at the source. The quality indicator is defined as the ratio of the effective energy used (during the same unit of time) and minimal energy. It shows the efficiency of the entire water supply system, which is determined by factors such as the efficiency of pumps, locations of reservoirs, and water loss in the network. The results of calculations are used to establish a relationship between the value of the quality indicator and the energy-reduction possibilities; this relationship permits a water supplier to evaluate how economically a water supply system uses its energy. Includes 11 references, tables, figures.