The Underground Injection Control Program (UIC) protects ground water quality by regulating the disposal of fluids into the subsurface. Most UIC wells or injection wells are simple devices that allow fluids into the shallow subsurface under the force of gravity. For example, in Washington State (Washington) thousands of UIC wells, mainly dry wells, are located along parking lots and roads to manage stormwater runoff. The potential for ground water contamination from UIC wells can occur and is dependent on the well construction and location, the volume and quality of the fluids injected and the hydrogeologic setting.

The UIC Program, authorized by the Safe Drinking Water Act, is administered under Title 40 Code of Federal Regulations (CFR) part 144. Washington Department of Ecology was delegated authority by the Environmental Protection Agency (EPA) in 1984 to administer the program (RCW 43-21A.445). State regulation Chapter 173-218 WAC (Underground Injection Control Program) is used to administer the program.

What are Injection Wells?

Injection wells are man-made or improved holes in the ground, deeper than they are wide at the ground surface, or an improved sinkhole or a sub-surface fluid distribution system. They are used to release or dispose of fluids underground. Examples include sumps, drywells, drainfields and infiltration trenches that contain perforated pipe. A fluid is any flowing matter, regardless of whether it is in a semisolid, liquid, sludge, or gaseous state. The fluid may be injected for a beneficial use (e.g. ground water recharge or at an aquifer remediation site) or potentially harmful (e.g. misuse of a septic system by accepting fluids other then sanitary waste).

EPA groups injection wells into five classes, depending on the type of waste to be disposed in them:

Program Requirements

There are two main requirements of the program:

  1. A non-endangerment performance standard must be met, prohibiting injection that allows the movement of fluids containing any contaminant into ground water. In Washington, all ground water is considered a potential source of drinking water.
  2. All well owners must provide inventory information by registering their wells with Ecology (or with EPA, Region 10, if the wells are located on tribal land).

For more information visit the registration form page at


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Last updated December 2012