Groundwater monitoring is performed in a number of situations with varying objectives. It involves measuring the physical and/or chemical properties of groundwater on a periodic basis. Concentrations of contaminants are frequently monitored to determine if they are increasing, decreasing, or remaining in the same range. Monitoring is also performed at and in the vicinity of water supply sources to determine the quality and trends of indicators of water quality. Groundwater monitoring programs normally involve a network of monitoring or observation wells or microwells.

The drawing on the right indicates a shallow overburden aquifer monitoring well and some its basic features. A well of this type facilitates measurement of groundwater elevation and permits sampling to test the chemistry of the groundwater.

For information on groundwater depth and elevation measurement and instrumentation, click here.  The detection of  non-aqueous phase liquid (NAPL) floating on groundwater and methods of measurement are discussed here.