U.S. Environmental Protection Agency 

Office of Research and Development 1

HYDRAULIC FRACTURING RESEARCH STUDY

Why is EPA Studying Hydraulic Fracturing?

Natural gas plays a key role in our nation’s clean 

energy future and hydraulic fracturing is one way of 

accessing this vital resource. Over the past few 

years, the use of hydraulic fracturing for gas 

extraction has increased and has expanded over a 

wider diversity of geographic regions and geologic 

formations. It is projected that shale gas will 

comprise over 20% of the total U.S. gas supply by 

2020. Given this expansion and increasing concerns, 

EPA announced in March 2010 that it will study the 

potential adverse impact that hydraulic fracturing 

may have on drinking water.

EPA has sought advice regarding the potential scope 

of the study plan from EPA’s Science Advisory Board

(SAB) Environmental Engineering Committee, an

independent, external federal advisory committee. 

The SAB’s input will help ensure that a sound 

scientific approach is used to develop the study plan.

During this summer, EPA will conduct a series of 

meetings to receive broad, balanced input on the 

study plan from stakeholders in key regions affected 

by hydraulic fracturing.

EPA will use the results from the study to help 

evaluate potential risks associated with hydraulic 

fracturing in an effort to protect America’s 

communities and resources.

What is Hydraulic Fracturing?

Hydraulic fracturing is a well stimulation process 

used to maximize the extraction of underground 

resources – oil, natural gas and geothermal energy. 

The hydraulic fracturing process includes the 

acquisition of source water, well construction, well 

stimulation, and waste disposal. 

Hydraulic fracturing involves the pressurized 

injection of fluids commonly made up of water and 

chemical additives into a geologic formation. The 

pressure exceeds the rock strength and the fluid 

opens or enlarges fractures in the rock. As the 

formation is fractured, a “propping agent,” such as 

sand or ceramic beads, is pumped into the fractures 

to keep them from closing as the pumping pressure 

is released. The fracturing fluids (water and 

chemical additives) are then returned back to the 

surface. Natural gas will flow from pores and 

fractures in the rock into the well for subsequent 

extraction.

Wells used for hydraulic fracturing are drilled 

vertically, vertically and horizontally, or directionally 

(Figure 1 depicts vertical and horizontal drilling). 

Wells may extend to depths greater than 8000 feet 

or less than 1000 feet, and horizontal sections of a

well may extend several thousands of feet away 

from the production pad on the surface.
U.S. Environmental Protection Agency EPA/600/F-10/002 June 2010 

Office of Research and Development 2

What is the Connection Between Water and 

Hydraulic Fracturing?

Water is needed during the process, and it is a 

central component of the waste products. Potential 

impacts to drinking water supplies have been 

suggested from many recent reports. 

Fracturing fluids can be up to 99% water. The 

volume of water needed for hydraulic fracturing 

varies by site and type of formation. Fifty thousand 

to 350,000 gallons of water may be required to 

fracture one well in a coalbed formation while two 

to five million gallons of water may be necessary to 

fracture one horizontal well in a shale formation. 

Water used for fracturing fluids is acquired from 

surface water or groundwater in the local area.

Wastewaters from the hydraulic fracturing process

may be disposed in several ways. For example, the 

flowback water following fracturing may be returned 

underground using a permitted underground 

injection well, discharged to surface waters after 

treatment to remove contaminants, or applied to 

land surfaces. Not all fracturing fluids injected into 

the geologic formation during hydraulic fracturing 

are recovered. Estimates of the fluids recovered 

range from 15-80% of the volume injected 

depending on the site. Some companies reuse

flowback to hydraulically fracture more than one 

well as a way of conserving water and recycling the 

fluids.

Public concerns have focused recently on the

impacts of the hydraulic fracturing process used 

during natural gas production from shale and 

coalbed methane formations. 

Potential risks to surface and underground sources 

of drinking water might occur at various points in the 

hydraulic fracturing process. The likelihood of those 

risks causing drinking water contamination will be 

evaluated during the EPA hydraulic fracturing study. 

Contaminants of concern to drinking water include 

fracturing fluid chemicals and degradation products 

and naturally occurring materials in the geologic 

formation (e.g. metals, radionuclides) that are 

mobilized and brought to the surface during the 

hydraulic fracturing process.

REFERENCES:

http://www.epa.gov/ogwdw000/uic/wells_hydrofrac.html

http://www.epa.gov/safewater/uic/wells_coalbedmethanestudy.html

EPA is interested in receiving comments on the proposed 

hydraulic fracturing research study. Please submit your 

comments to EPA at hydraulic.fracturing@epa.gov, or 

send written comments to Jill Dean, 1200 Pennsylvania 

Ave. NW, Mail code 4606M, Washington, DC 20460.