Definition - What does Water Column mean?
A water column is defined as a hypothetical cylinder of water extending from the surface to the bottom of the water body in consideration. Water columns are typically measured in inches and are used as non-SI units for pressure.
Pressure expressed in inches of water column (inch wc) is defined as the pressure exerted by a column of water 1 inch in height.
Trenchlesspedia explains Water Column
As a measurement of pressure, water columns can be used to determine small pressure differentials such as the difference in pressures across a pipeline or shaft.
The concept of a water column is also employed in the installation of cured-in-place piping (CIPP). The resin-saturated liner is inverted into the host pipe using the hydrostatic pressure exerted by a column of water. The pressure created by the water column presses the liner against the walls of the host pipe to ensure that excess resin is forced into cracks, joints and other irregularities thereby ensuring proper structural bond between the host pipe and the (CIPP).