Living near oil or natural gas well doesn't really affect drinking water

There have been concerns that living near an oil or natural gas well could affect drinking water, but according to a team of researchers, the risk is actually quite low.

Does living near an oil or natural gas well affect your drinking water? "The answer to that question is usually 'no,' but there are exceptions," said Stanford University's Rob Jackson said.

Jackson added that they have found a number of homes near active wells with very high levels of natural gas in the tap water. Where the chemistry suggests contamination, the problem usually lies with the integrity of the well, either the cementing used to isolate it from the surrounding rock and water or the steel casing that allows gas and oil to flow upwards.

Most documented cases of groundwater contamination were caused by poorly constructed wells, he said, pointing to a widely publicized case in Parker County, Texas. At that site, the company cemented very near the surface and deep underground, but they put no cement for 4,000 feet in between, he explained, adding the gap allowed gases to move up and down freely like a chimney and contaminate the drinking-water supply."

Besides structural issues, Jackson and his colleagues have identified problems associated with hydraulic fracturing, or fracking. This technology uses pressurized sand, water and chemicals to crack open rocks and release trapped reservoirs of oil and gas.

Fracking wells are often installed a mile or more below the surface, far from underground sources of drinking water. But in a recent study, Jackson found that at least 2,600 wells in U.S. have been fracked at depths shallower than 3,000 feet, some just hundreds of feet below the surface.

The study has been presented at 2016 AAAS Annual Meeting.