Solinst Model 404 WaTerra Pump
The WaTerra Pump is a simple, reliable inertial pump which uses an age-old, proven technology, in an elegant manner uniquely adapted to the needs of modern groundwater monitoring. The pump consists of a riser tube with a one-way valve at the foot and a surface pumping mechanism.
The valve allows water to enter the tubing as it is pushed downwards, and retains the water when the tube is pulled upwards again. The inertia of the water itself provides the force to carry it up to the surface whenever the tube is being pumped up and down. The water travels in a continuous column, with little disturbance, thus retaining volatiles.