This article provides an overview of alternative sources of energy for water systems and presents methods for saving energy from conventional sources. Alternative sources of energy such as active and passive solar systems, photovoltaic cells, and wind power are addressed. Comparative costs of natural gas, electricity, and oil are presented. Methods of saving energy in distribution and pumping systems relating to opening valves, reducing operating pressure, reducing pipe friction, running pumps, matching pump curves, using energy-efficient motors, filling elevated storage facilities at night, using variablespeed pumps, and using computer controls to take advantage of nighttime power costs are discussed. Methods for saving energy in water treatment plants addressed include: balancing heating, ventilating, and air conditioning systems; installing efficient lighting fixtures; designing treatment plants with consideration for energy demands of treatment components; minimizing the hydraulic gradient; using coagulants that require low energy expenditures; using sand drying beds or sludge dewatering and drying lagoons instead of energy-intensive sludge dewatering equipment; using sedimentation basins with sloping hopper bottoms; using alternatives to energy-intensive granular activated carbon filtration to reduce trihalomethanes; using computers to monitor backwash for conventional filters; using elevated storage for backwash water; elevating the clearwell for declining-rate filtration systems; using chemical analyzers to prevent overfeeding of chemical doses; and using gravity-flow systems whenever possible. Includes reference, table, figures.