Water Filtration

Many homeowners unhappy with the quality of their drinking water are turning more and more to either a variety of water filtration systems or to one source or another of bottled water, although the latter is slowly becoming less prevalent every day. However, for those whose source of drinking water is a well or for those who live near a well, wells have become a major health issue making either of these choices far better than doing nothing. Why? People have been drinking from wells for centuries, haven’t they? Yes, they have, but since the Industrial Revolution in the late 19th century, more and more wells have become increasingly contaminated, and one particular type of well that has suffered more than most is called an injection well.

What is an injection well?
An Injection well is a device that places fluid deep underground into porous rock formations, such as sandstone or limestone, or into or below the shallow soil layer. These fluids may be water, wastewater, brine (salt water), or water mixed with chemicals.

The Underground Injection Program (UIC) defines an injection well as:

• A bored, drilled, or driven shaft, or a dug hole that is deeper than it is wide,
• An improved sinkhole, or
• A subsurface fluid distribution system.

How an injection well looks (is constructed) depends on the fluid injected and the depth of the injection zone. For example, deep wells that inject hazardous wastes into isolated formations far below the Earth’s surface are designed to provide multiple layers of protective casing and cement. Shallow wells that inject into or above drinking water sources are usually of simple construction and inject non-hazardous fluids.

What are injection wells used for?
Injection wells have a range of uses that include waste disposal, enhancing oil production, mining, and preventing salt water intrusion. Widespread use of injection wells began in the 1930s to dispose of brine generated during oil production. Injection effectively disposed of unwanted brine, preserved surface waters, and in some formations, enhanced the recovery of oil. In the 1950s, chemical companies began injecting industrial wastes into deep wells. As chemical manufacturing increased, so did the use of deep injection. Injection was a safe and inexpensive option for the disposal of unwanted and often hazardous industrial by-products.

In an effort to turn things around, in 1974, Congress passed the Safe Drinking Water Act (SDWA). Part of SDWA required EPA to report back to Congress on waste disposal practices, and develop minimum federal requirements for injection practices that protect public health by preventing injection wells from contaminating underground sources of drinking water (USDWs).

The UIC Program protects USDWs from endangerment by setting minimum requirements for injection wells. All injection must be authorized under either general rules or specific permits. Injection well owners and operators may not site, construct, operate, maintain, convert, plug, abandon, or conduct any other injection activity that endangers USDWs.

The purpose of the UIC requirements is to:

• Ensure that injected fluids stay within the well and the intended injection zone, or
• Mandate that fluids that are directly or indirectly injected into a USDW do not cause a public water system to violate drinking water standards or otherwise adversely affect public health.

For more information about how the UIC regulations protect ground water visit: www.epa.gov/UIC

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