At least eight studies across the United States over the past three years have confirmed that fracking does not contaminate groundwater.

From Colorado State University to Yale University to the U.S. Geological Survey, experts have found no evidence that hydraulic fracturing, commonly known as “fracking,” is causing contaminants to seep into drinking water wells

“There isn’t a chronic, the-sky-is-falling type of problem with water contamination,” Ken Carlson, a CSU professor of civil and environmental engineering, told The Coloradoan.

Carlson’s team developed a system to monitor groundwater quality at oil and natural gas sites in real time. The team publishes their results on a webpage called “Colorado Water Watch,” and to date, they have found no evidence of groundwater contamination from oil and natural gas production.

Our funders, the groups that had given us funding in the past, were a little disappointed in our results. We haven’t seen anything to show that wells have been contaminated by fracking.” – Amy Townsend-Small, the lead researcher of a University of Cincinnati study

This year alone, the USGS failed to find any instances of water contamination from fracking in 116 wells in energy producing areas of Arkansas, Texas and Louisiana, and The Academy of Medicine, Engineering and Science of Texas (TAMEST) released a study concluding that contamination of drinking water from fracking “has not been observed in Texas” and is “highly unlikely” to contaminate drinking water aquifers.

Similar studies in Ohio, Wyoming and West Virginia have also found no evidence of groundwater contamination from fracking or other oil and natural gas production. And a massive, 5-year study by the U.S. Environmental Protection Agency concluded there is “no evidence of widespread, systemic impacts on drinking water” from fracking.

Even studies which received funding from anti-fracking groups have reached the same conclusions.

Colorado’s oil and natural gas industry have used innovative techniques and technologies to reduce water use and ensure the safety and purity of local water sources.

Experts cite several precautions taken by the industry as reasons for the continued safety of groundwater in areas of oil and gas production, including the practice of lining wellbores with multiple layers of cement-sealed steel casing over the ground water zones.

As a backup to the technology in place, groundwater quality is monitored in Colorado to make sure that these safeguards continue to work. In 2013, Colorado became the first state in the nation to require groundwater sampling both before and after drilling.

The fracking process accounts for only 0.001 percent of total water use in Colorado. In contrast, agriculture uses 85 percent of the state’s water, according to the Colorado Division of Water Resources.

Even so, oil and natural gas companies are actively pursuing steps to reduce water use even further while safeguarding against contamination.