• A wall or bank to hold water back. • An instrument for measuring or ascertaining the depth or quantity of water, or for indicating the height of its surface, as in the boiler of a steam engine. See Gauge.
Wa'ter gauge` [ Written also water gage .] 1. A wall or bank to hold water back. Craig. 2. An instrument for measuring or ascertaining the depth or quantity of water, or for indicating the height of its surface, as in the boiler of a steam engine. See Gauge . 
(standard U-tube) Instrument that measures differential pressures in inches of water.
[n] - gauge for indicating the level of water in e.g. a tank or boiler or reservoir
water gage noun gauge for indicating the level of water in e.g. a tank or boiler or reservoir