Answer to Question #10693 Submitted to "Ask the Experts"

Category: Environmental and Background Radiation — Water

The following question was answered by an expert in the appropriate field:


The level of natural uranium in my well water is 323 µg L-1. I installed a reverse osmosis unit for drinking and cooking purposes. Is the elevated level safe for showering, washing clothes, or watering my vegetable garden? At what levels would the water be unsafe for showering or washing?


The primary hazard from uranium in well water is the chemical toxicity that could result from ingesting high levels of uranium; the radiation hazard is secondary (see Ask the Experts Question 9703). With that in mind, the Environmental Protection Agency (EPA) has set the limit for uranium in drinking water at 30 µg L-1 (see Ask the Experts Question 10627). The uranium levels in your well water are more than 10 times the EPA limit, so you are wise to use water treated by reverse osmosis for drinking and cooking.

Irrigation water is another way of ingesting uranium in well water; however, research suggests that irrigating plants with water uranium levels much higher than yours would not result in health effects. A study by Orquidia Neves and Maria Manuela Abreu showed that lettuce, potatoes, and beans grown in uranium-contaminated soil and irrigated with uranium-contaminated water at levels greater than 900 µg L-1 had uranium levels 50 to 100 times less than the level at which health effects could be expected (Neves and Abreu 2009).

For bathing and showering, the Centers for Disease Control and Prevention note that water containing uranium is not a health concern; this is echoed by the EPA. The same would hold true for washing clothes in your well water. Because chemical toxicity by ingestion is the primary health hazard for uranium in water, water that is safe for irrigation should also be safe for bathing and washing clothes.

Linnea E. Wahl, CHP

Neves O, Abreu MM. Are uranium-contaminated soil and irrigation water a risk for human vegetable consumers? Ecotoxicology 18:1130–1136; 2009.

Ask the Experts is posting answers using only SI (the International System of Units) in accordance with international practice. To convert these to traditional units we have prepared a conversion table. You can also view a diagram to help put the radiation information presented in this question and answer in perspective. Explanations of radiation terms can be found here.
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