Peristaltic pumps operate at the surface, using tubing suspended in the well. During use, water is slowly drawn up the tubing via a vacuum created by the pump at the surface. These pumps are most effective for low-flow water sampling, in wells with depth to water of less than 25 feet.
Bladder pumps can be effective for water analysis up to 1,000 feet. These devices utilize a submerged pump with a controller at the surface. Compressed air is supplied through tubing, which squeezes the bladder to move a minimally-agitated water sample through discharge tubing to the surface.
Battery-operated 12-VDC pumps are portable and achieve pumping rates suitable for rapid well-purging. The pump is lowered into the water, suspended on electric cable and water discharge tubing, while controllers enable low-flow sampling.
Well development pumps remove silt and sand from outside the well screen so that groundwater can flow into the monitoring well. Unlike electric pumps, pneumatic well development pumps are not damaged by the grit as it is removed.
Pumps vary greatly in their functionality – it may be more practical to rent than to buy for every occasion.