Here's a quote from an even-handed treatment of the EPA's recent write-up of groundwater contamination in Wyoming near a fracking site:

"The agency also stressed that the findings are unique to Pavillion, where fracturing has taken place both in and below the drinking water aquifer and very close to drinking water wells — conditions that are not common elsewhere in the U.S. The region has been home to oil and gas drilling since the 1950s, and some of the 169 gas production wells in the area were fractured at points just 1,220 feet below the ground.

By contrast, in South Texas, energy companies are extracting natural gas from the Eagle Ford shale formation at depths ranging from 4,000 to 14,000 feet below the surface"

It short, it depends on where and how the process is done. No surprise. Strikes me that that some sensible regulation of the process would not be unwarranted, though.