Casagrande filter unit is used to measure the water pressure in permeable soil. Filter unit is made in syntherised high density polyethylene. It is available in different models to suite all the customer applications. Filter units have threaded cap joint with two 0.5" twin tubes or with a 1.5" single tube.

Standpipe piezometers are used to monitor the ground water table. The standpipe filter unit consists of a slotted tube covered by geotechnical fabric for filtered water entry.