Then why is fracking so controversial? This is the second biggest question after you’ve answered What is fracking? The environmental impact of widespread fracking isn’t yet known. It requires an enormous amount of water—as much as 2-5 million gallons for a horizontal well in a shale formation. This water is generally taken from local resources. In addition to the chemicals initially added, the wastewater that’s pumped back out can also contain many other contaminants and toxins, including radioactive material. And, according to The Geological Society of America (GSA), “Estimates of the fluids recovered range from 15-80% of the volume injected depending on the site.” That leaves quite a bit of contaminated water left to leach into the ground.