Uranium in Well Water
Uranium dissolves out of granite and some sandstones into groundwater across the Rockies, the Southwest, New England and parts of the Carolinas. It is a kidney toxin at levels found in wells, and it travels with radon.
Likely causes
- Naturally occurring uranium in granite and sedimentary aquifers
- Former mining areas
Tests to order
- Uranium
- Gross alpha
- Radon in water
- Radium
Treatment options
- Reverse osmosis at the tap
- Anion exchange whole-house unit
- Blend with a second source
The limit and the effect
The federal limit for uranium is 30 micrograms per liter. Wells in the Colorado Front Range, the Sierra foothills, New England granite and the Carolina Piedmont regularly exceed it, sometimes by ten times. The concern at these levels is chemical rather than radiological: uranium damages the kidneys with long-term exposure. It has no taste and no color.
A gross alpha screen is the cheap first step
Many labs offer a gross alpha test that screens for all the alpha-emitting elements at once. Above 15 pCi/L it triggers the specific uranium and radium tests. If you are in a known uranium area, skip the screen and order uranium directly; it is $30 to $60. Add radon in water, since the same rock produces both.
Removing it
Reverse osmosis at the kitchen tap removes 95% or more of uranium from drinking and cooking water, $300 to $800, and is the answer for most homes because uranium is not absorbed through skin. If you want every tap treated, an anion exchange system sized for uranium, $1,500 to $3,500, works well; the spent resin has to be handled as low-level waste, so use an installer who has done it before. Softeners remove a little uranium at best and are not a treatment.
Is uranium water radioactive enough to worry about?
The radiation dose from drinking it is small. The kidney toxicity is the issue, and it is well documented.
Can I water the garden with it?
Yes. Plants take up very little uranium, and it does not concentrate in vegetables at levels of concern.