Water and Wastewater Terms Beginning P

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piezometer (pie-ZOM-uh-ter)

An instrument used to measure the pressure head in a pipe, tank, or soil. For pipes and tanks, it usually consists of a small pipe or tube. One end is connected or tapped through the wall of the pipe or tank being measured. The other end is most often open to the air, in which case the height of the water in the tube above the connection is the pressure head in inches or feet. For high pressures the tube may be connected to a mercury column in which case the pressure head is expressed in inches of mercury. For soil applications, the tube is connected to a permeable tip which is then buried in or driven into the soil. In this case, the piezometer measures the pore pressure of water in the soil. Also see manometer.