Rotapump is an inertial lift wellhead pump that can pump water from depths up to 150 feet or more. The pump drives a pumping tube with a check valve installed to the desired pump depth.The pump can be operated with a manual drill, rechargeable portable drill, or a 450 Watt DC motor that mounts on the pump. A pulse width modulator speed controller with selected input voltage of 12, 24, or 48 volts is offered for precise flow control (50 ml/min to 4 gpm). Decontamination is not required between wells if dedicated pumping tubes are used. The pump is self priming from any depth and easily pumps sediment-laden water for monitoring well development.Sediment-free low-flow groundwater purging and sampling is easily done using a small diameter pumping tube placed inside a slightly larger stilling tube that is hung in the well.The pump is rugged, relatively light (24 lbs), and easily set up on at-grade wellheads or on well housings that extend above grade.