Sampling Groundwater Using Drop Tubes

solinst 407 bladder pump groundwater samplers

Solinst Model 407 Bladder Pumps


illustration show drow tube assambly being deployed below a solinst bladder pump or double valve pump to capture groundwater samples at greater depths

Solinst Model 407 Bladder Pumps

Drop Tube Assemblies

Solinst Bladder Pumps and Double Valve Pumps can lift samples from depths of 150 m (500 ft) below grade and below static water level, respectively. However, samples from greater depths can be obtained using a drop tube assembly.

A drop tube assembly is easily installed onto an existing pump – it can even be done in the field.

The drop tube assembly allows the connection of any length of tubing to the bottom of your pump, and the filtered inlet to the bottom of this tubing extension.

This means you can place the screened filter intake of the pump as deep as necessary to access the desired sampling zone.

solinst 1 point 66 inch diameter pump drop tube assembly shown with check balls orings clampst and connetors for part 103231

1.66" dia. Pump Drop Tube Assembly (pt#103231 for 407/408)


solinst 1 inch diameter pump drop tube assembly shown with clamps part number 107902

1" dia. Pump Drop Tube Assembly (pt# 107902 for 407/408)


Operation Limitations

The pump is operated in the same manner as those without a drop tube, maintaining the same sample integrity.

During operation the pump must remain above the maximum depth of 150 m (500 ft). The drop tube can sample from any depth, but the static/pump level must remain above the 150 m (500 ft) maximum and the entire pump body must remain submerged during sampling.


For sampling isolated zones from submerged depths as much as 1200 m (4000 ft), Solinst offers the Model 425-D Deep Sampling Discrete Interval Sampler.