Researchers from Yale University have concluded that hydraulic fracturing, or fracking, doesn’t contaminate drinking water. “[There is] no evidence of association with deeper brines or long-range migration of these compounds to the shallow aquifers” The study
was published in the prestigious "Proceedings of the National Academy of Science of the United States of America," October 27, 2015 (abstract is here
). The largest of its kind, the study sampled 64 private water wells near fracking sites to determine if they could be contaminated by fracking fluids.
“[The chemicals] are likely not a threat to human health,” said Brian Drollette, the study’s first author who is a chemical and environmental engineering graduate student.
The Yale researchers found essentially no contamination in well water, and the amounts they did detect were hundreds or thousands of times smaller than can be detected by commercial labs.