Pore water pressure
（重定向自Pore fluid pressure）
![A vibrating wire piezometer. The vibrating wire converts the fluid pressures into equivalent frequency signals that are then recorded.](/Images/godic/202502/03/Vibrating_wire_piezometer_from_USBR_6515-09_Fig._14725.png")
![Electronic tensiometer probe: (1) porous cup; (2) water-filled tube; (3) sensor-head; (4) pressure sensor](/Images/godic/202502/03/Tensiometer4725.png")
![](/Images/godic/202502/03/Soil_profile4725.png")
Pore water pressure (sometimes abbreviated to pwp) refers to the pressure of groundwater held within a soil or rock, in gaps between particles (pores). Pore water pressures in below the phreatic level (see also groundwater) are measured in piezometers. The vertical pore water pressure distribution in aquifers can generally be assumed to be close to hydrostatic.