Monitoring of Drinking Water Supplies Near Natural Gas Drilling

Posted: May 9, 2010

Drilling in the Marcellus Shale has many people concerned about their private water wells. Here are some suggestions and steps to take to monitor your drinking water supplies.

Written by Bryan Swistock

Increased gas drilling in the Marcellus Shale throughout Pennsylvania has concerned many of the state’s 3.5 million residents who use private water wells or springs. These concerns stem from the use of drilling chemicals, production of large amounts of waste fluids, and possibility of methane migration from the gas well into adjacent groundwater aquifers. 

Existing state regulations specify certain gas well construction practices to protect groundwater supplies including setbacks between water supplies and gas drilling, protective casing and cement, and requirements for storage of chemicals and waste fluids. Gas drilling companies are also presumed responsible for contamination of drinking water supplies within 1,000 feet of a gas well site.  The presumed responsi-bility for water supplies typically results in thorough, voluntary testing of water wells and springs by state-accredited water testing labs contracted by the drilling company.  Water supply owners should allow this testing to occur but confirm that the person collecting the water samples is a representative of a state-certified water testing laboratory.

In many cases, additional monitoring of water quality can be a good idea for water supply owners, especially if the supply is located more than 1,000 feet from the gas well site where testing is rarely done by the drilling company.  All water testing should be arranged through a state accredited water testing laboratory.  It is important to remember that water samples collected to document impacts from gas well drilling should not be collected by the water supply owner.  Rather, water samples should be collected by an unbiased professional employed by or representing the state accredited testing lab. This “third-party” or “chain-of-custody” sampling typically adds $20 to $50 to the cost of water testing but will be vital to the admissibility of the results in any legal action related to pollution of a private water supply. You can expect to pay $200 to $500 or more to have a pre-drilling water sample collected and analyzed by a certified water testing laboratory depending on the complexity of the test package.  The water testing labs can assist with selection of water quality parameters and many offer standard packages of tests that correspond to gas well drilling activities. Basic testing should include total dissolved solids (TDS), chloride, barium, and methane gas at a minimum. 

Diminished or lost water supplies resulting from gas well drilling have occurred but are rare. When this does occur, it is usually an obvious, complete loss of water rather than a subtle decrease in water yield. Well and spring owners that wish to document water supply conditions before and after gas well activities would need to hire a professional water well contractor or hydrogeologist to independently measure and document these conditions.

During and after gas drilling, water supply owners should watch for obvious signs of problems such as muddy water, foaming, spurting faucets, metallic or salty tasting water, changes in water odor, or reduced quantity of water.  Contact the PA Department of Environmental Protection immediately if you notice any of these problems during gas drilling.

For more information on protecting your water supply in areas of gas drilling, consult the Penn State Cooperative Extension web site at