To monitor water level at a particular location, either an existing well/borehole is used or a borehole is drilled down to the aquifer that contributes most to the water table. A casing pipe is installed in the borehole to prevent the borehole wall from collapsing. At the level of the aquifer, a highly porous filter is provided at the lower end of the casing pipe. The filter generally consists of a section of slotted pipe covered with geotextile to prevent soil particles from clogging the borehole. The level of water in such a borehole or well corresponds to the water table at that location. The water level is generally referenced to mean sea level and is known as the elevation of the water table.
The Encardio-rite model EWLR-101 is also used for monitoring water level in a river, lake or reservoir by lowering the sensor in a gauge well.