A piezometer is either a device used to measure liquid pressure in a system by measuring the height to which a column of the liquid rises against gravity, or a device which measures the pressure (more precisely, the piezometric head) of groundwater at a specific point. A piezometer is designed to measure static pressures, and thus differs from a pitot tube by not being pointed into the fluid flow.

Observation wells give some information on the water level in a formation, but must be read manually. Electrical pressure transducers of several types can be read automatically, making data acquisition more convenient.