Arsenic and other well contaminants

What else to test for

Oklahoma DEQ says high levels turn up in both shallow and deep wells anywhere in that aquifer, so the risk is unknown until the water is tested.

The Oklahoma DEQ fact sheet lists the federal limits in micrograms per liter: arsenic 10, chromium 100, selenium 50 and uranium 30.

Oklahoma DEQ notes that the state does not require private well testing, but owners may want these metals checked; DEQ's state lab supplies sample kits.

Texas A&M AgriLife Extension reports naturally high arsenic in the southern High Plains (Ogallala aquifer), several West Texas counties and South Texas (Gulf Coast aquifer).

Texas A&M AgriLife Extension says lead rarely occurs naturally in well water; it usually comes from corroding pipes, solder and brass fixtures, and lead pipes are most likely in homes built before 1930.

For a lead test, Texas A&M AgriLife Extension describes a first draw sample after water has sat in the pipes 6 hours or more, plus a second sample after running the tap at least 5 minutes.

Texas A&M AgriLife Extension says fluoride can occur naturally from rock and soil; the primary drinking water standard is 4.0 ppm, and higher levels may cause bone problems.

Sources: Oklahoma: central aquifer metals; Texas: where arsenic is found; Lead comes from plumbing; Fluoride limit

Radon in water

EPA describes radon as a colorless, odorless, tasteless gas from the natural breakdown of uranium in the ground.

EPA says radon in water is only a concern when the water comes from underground, such as a well, and not every well has it.

Based on a National Academy of Sciences report, EPA estimates radon in drinking water causes about 168 cancer deaths a year.

EPA says 89 percent of that risk is lung cancer from breathing radon released from tap water into indoor air, and 11 percent is stomach cancer from drinking it.

EPA recommends that private well owners test their drinking water for radon, using a lab the state certification office can point to.

EPA says the most effective fix is point of entry treatment with granular activated carbon or aeration; carbon costs less but collects radioactivity, so used filters need special handling.

Texas A&M AgriLife Extension notes that most of the radon people breathe comes from the soil under the house, not from water.

Texas A&M AgriLife Extension lists radium, radon and uranium as the most common radioactive elements in drinking water, found more often in well water than surface water.

Sources: What radon is; Most radon comes from soil