Water accounts for about 90 percent of the fracturing mixture and sand accounts for about 9.5 percent. Chemicals account for the remaining one half of one percent of the mixture. There are several ways oil and natural gas companies manage the use of fracturing fluids, depending on what specifically is in them, the presence of usable groundwater or surface waters, geography, and local, state, and federal regulations.
It's our experience in Pennsylvania that we have not had one case in which the fluids used to break off the gas from 5,000 to 8,000 feet (1,500-2,400 m) underground have returned to contaminate ground water.
John Hanger, former secretary of the Pennsylvania Department of Environmental Protection
Spent or used fracturing fluids are normally recovered at the initial stage of well production and recycled in a closed system for future use or disposed of under regulation, either by surface discharge where authorized under the Clean Water Act or by injection into Class II wells as authorized under the Safe Drinking Water Act. Regulation may also allow recovered fracturing fluids to be disposed of at appropriate commercial facilities. Not all fracturing fluid returns to the surface. Over the life of the well, some is left behind and confined by thousands of feet of rock layers.
The Ground Water Protection Council and the Interstate Oil and Gas Compact Commission have created FracFocus, a hydraulic fracturing chemical registry website where you can search for information about the chemicals used in the hydraulic fracturing of oil and gas wells. Drilling companies have been strongly supportive of this registry.