All water quality samples collected from 28 wells near Houston did not contain uranium and radioactive elements above the U.S. Environmental Protection Agency’s (EPA) maximum contaminant level (MCL) for treated drinking water, a new study shows.

However, untreated ground water samples from two of the 28 municipal supply wells sampled did contain concentrations of naturally occurring arsenic above EPA’s MCL for treated drinking water. EPA’s MCL regulations only apply to treated drinking water; they do not apply to untreated source water, and are used only as a reference. Arsenic is a naturally occurring element in the environment. Its presence in ground water is largely the result of minerals dissolving naturally over time as rocks and soils weather.

U.S. Geological Survey (USGS) scientists examined source (untreated) water collected from 28 municipal wells before treatment or blending, rather than the finished (treated) drinking water that water utilities deliver to their customers. Samples are analyzed to assess variations in the water quality of the Gulf Coast Aquifer throughout the region. Water samples were analyzed for arsenic, uranium, radioactive elements and other naturally occurring materials.

Results from this USGS study, done in cooperation with the City of Houston, can be found on the USGS Texas Water Science Center Web site. Click on this link to read more.