ABSTRACT
Early water systems used reciprocating positive displacement pumps powered by steam engines to obtain the pressure needed to supply water to customers. These pumps have essentially all been replaced with centrifugal pumps, which are much more efficient. The only types of positive displacement pumps used in current water and wastewater systems are some types of portable pumps used to dewater excavations, pumps used to convey sludge/biosolids, and chemical feed, or metering, pumps (AWWA, 1996).
