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Safe Water Levels for Drinking

In the United States, the Environmental Protection Agency regulates public drinking water by monitoring levels of arsenic, lead, chlorine, fluoride and microbial contaminants such as cryptosporidium. Safe drinking water is often scarce in the developing world. In Africa, for example, only 46 percent of people have access to clean water.

  1. Arsenic

    • Arsenic is a naturally occurring substance in soil and groundwater which can cause cancer and various other ailments. Formerly, the maximum standard for arsenic in drinking water was 50 parts per billion. In 2002, the EPA reduced this to 10 ppb, due to research suggesting that people consuming water with 20 ppb arsenic have a 0.7 percent increased risk of developing cancer in their lifetime. Arsenic is especially a problem in private wells.

    Lead

    • The EPA suggests that if water has a lead content above 15 ppb, you should take action to replace old pipes, filter water or drink bottled water. The actual enforced lead standard is higher than this, however. Children are especially susceptible to lead poisoning.

    Fluoride

    • A small amount of fluoride in water is usually considered to be beneficial for dental health. Higher concentrations of fluoride can be toxic. The current EPA standard for fluoride is 4 milligrams per liter of water, but a study by the National Research Council suggested that this standard is too high and should be lowered.

    Cryptosporidium

    • There are no specific standards for the number of cryptosporidium cysts which are allowed in drinking water; even an extremely low concentration of this or other pathogens can cause outbreaks. The EPA requires that water treatment facilities take specific steps to prevent cryptosporidium contamination.

    Perchlorates

    • Perchlorates are a type of endocrine-disrupting compound that may have negative effects on human hormone production. There is a dispute as to how dangerous perchlorates are. One report by the EPA said that concentration as low as 1 ppb could have negative effects, while the Department of Defense claims that levels as high as 200 ppb are safe. Many water supplies in the United States have around 4 ppb perchlorates. There is no federal standard; only Massachusetts and California regulate perchlorate.

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