The Eno Scientific WS131 Flow Meter is designed to measure water flow for monitoring well drawdown and usage. It uses a modular design consisting of a PVC housing and an electronic sensor module that easily attaches to the housing using a hand tightened ring nut. With the sensor in place, electrical pulses are generated as water moves past the paddle wheel which can be interpreted as water volume by an Eno Scientific water level meter, the Well Sounder 2010 PRO, or other device. When the test is complete, the sensor can be removed and replaced with an inexpensive plug using the same kind of hand tightened ring nut. This leaves the sensor port available for future testing.