For continuous monitoring of water level in wells an automatic water-level sensor (AWLS) is required. The AWLS is comprised of a pressure sensor that is lowered far enough below the water table in a well to ensure that it will remain submerged throughout the monitoring period. The sensor measures a combination of hydrostatic and barometric pressures and records the data internally or transmits the reading by means of a communication cable to a data logger at the surface of the well where it is converted to depth to water and logged. The AWLS with a communication cable is somewhat more expensive than the internal-recording type but provides easier download of data without removing the sensor and allows for telemetry of data when real-time data access is desired. This type of AWLS comes with two different types of communication cables, one vented and the other non-vented.

Groundwater Measurement
Description Atmosperic Pressure Compensation Range Cost
DWLR with Telemetry & Vented Pipe Vented Pipe   1,25,000
DWLR with Telemetry without vented Pipe Atmosperic Pressure Sensor   1,25,000
DWLR without Telemetry None   1,00,000