Advantages and Disadvantages of Various Groundwater Sampling Devices  (modified from EPA/540/P-91/00 January 1991)

Device Advantages Disadvantages
  • The only practical limitations are size and materials
  • No power source needed portable
  • Inexpensive; it can be dedicated and hung in a well reducing the chances of cross-contamination
  • Minimal outgassing of volatile organics while sample is in bailer
  • Readily available
  • Removes stagnant water first
  • Rapid, simple method for removing small volumes of purge water
  • Time consuming, especially for large wells
  • Transfer of sample may cause aeration
Submersible Pump
  • Portable; can be used on an unlimited number of wells
  • Relatively high pumping rate (dependent on depth and size of pump)
  • Generally very reliable; does not require priming
  • Potential for effects on analysis of trace organics
  • Heavy and cumbersome, particularly in deeper wells
  • Expensive
  • Power source needed
  • Susceptible to damage from silt or sediment
  • Impractical in low yielding or shallow wells
Non-Gas Contact Bladder Pump
  • Maintains integrity of sample
  • Easy to use
  • Difficult to clean although dedicated tubing and bladder may be used
  • Only useful to approximately 100 feet in depth
  • Supply of gas for operation (bottled gas and/or compressor) is difficult to obtain and is cumbersome
Suction Pump
  • Portable, inexpensive, and readily available
  • Only useful to approximately 25 feet or less in depth
  • Vacuum can cause loss of dissolved gases and volatile organics
  • Pump must be primed and vacuum is often difficult to maintain
  • May cause pH modification
Inertia Pump
  • Portable, inexpensive, and readily available
  • Rapid method for purging relatively shallow wells
  • Only useful to approximately 70 feet or less in depth
  • May be time consuming to use
  • Labor intensive
  • WaTerra pump is only effective in 2-inch diameter wells