Class IV wells inject hazardous or radioactive fluids into or above underground sources of drinking water (USDWs). The EPA banned Class IV wells in 1984 because of the risks they pose to USDWs. Less than 32 waste clean-up sites with Class IV wells exist in the United States.1USEPA. (2022, January 26). Class IV shallow hazardous and radioactive injection wells. Retrieved 12/30/2022 from https://www.epa.gov/uic/class-iv-shallow-hazardous-and-radioactive-injection-wells.
Underground Injection Wells by Class
| Injection Well Class | Number of Injection Wells | Injection Wells Inspected |
|---|---|---|
| Class I | 830 | 453 |
| Class II | 181,431 | 84,317 |
| Class III | 28,327 | 406 |
| Class IV | 122 | 27 |
| Class V | 531,176 | 4,038 |
| Class VI | 2 | 0 |
Source: EPA2USEPA. (2020). Underground Injection Control Program Fact Sheet. EPA 816F19005 April 2020.
While new wells of this class are banned, sometimes undocumented or previously unknown sites are discovered, and they are given this status. Sometimes hazardous waste is disposed of in a Class V well, which automatically changes its status from Class V to Class IV.
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