The Hockessin Ground Water aquifer is now one of six Superfund sites that were announced by the Environmental Protection Agency.
Hockessin’s problems stem from dry cleaning pollutants known as PCE’s that have been found in the aquifer.
It covers a 32 acre area that runs through the Hockessin business district.
Residents with a well within a half-mile of the contamination and who do not have a water treatment system are urged to contact DNREC.
But regulators stress that the drinking water from the Artesian Resources Corporation has been filtered and is safe.