SOURCES OF WATER

Surface Water Surface water supplies are obtained from streams, rivers, lakes, and reservoirs. The quantity of water available from a surface supply can be determined with reasonable accuracy from yield studies that take into account the local effects of rainfall, runoff, evaporation and sedimentation rates, and other hydrological factors. Development of a surface supply usually requires pumps to transport raw water from the source to a treatment plant and to provide the head necessary for proper hydraulic operation of the treating facilities. Pumps utilized for this purpose are classified as low-lift pumps because relatively low discharge heads are required.

Selection of a specific type of pump for low-lift service is dependent on intake conditions. Because surface water supplies vary significantly in temperature, bacteria count, and turbidity at varying depths and because the water level may fluctuate considerably, it is necessary to provide some type of intake structure that will permit withdrawal of water at several elevations. Multiple intake ports equipped with trash racks and water screens provide this capability and provide protection from fish and debris. The design and location of the intake structure influence the selection of either a horizontal or vertical pump for low-lift service.

Groundwater In many areas of the United States where rainfall and runoff are sparse, significant supplies of water are available from underground sources. The groundwater table is formed when rainfall percolates through the soil and reaches...