Frequent Questions

If a facility is installing a Class I injection well, the well must inject beneath the lowermost underground source of drinking water (USDW). How does EPA define a USDW?

A USDW, as defined in 40 CFR 144.3 is an aquifer or its portion:

(a)(1) Which supplies any public water system; or

    (2) Which contains a sufficient quantity of ground water to supply a public water system; and

(i) Currently supplies drinking water for human consumption; or
(ii) Contains fewer than 10,000 mg/l total dissolved solids; and
(b) Which is not an exempted aquifer.




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