Summary of Report

Benefits of Safer Drinking Water: The Value of Nitrate Reduction

Contact: Stephen R. Crutchfield, 202-694-5460.

Consumers would be willing to pay $45 to $60 per household per month for a filter that reduced nitrates in drinking water to levels considered safe, if their drinking water exceeded the EPA minimum safety standard. Additional findings from a survey conducted in four regions of the United States showed that respondents would pay from $45 to $70 per month for a filter that would render their drinking water totally nitrate-free.

Ground water is an important source of drinking water, especially in rural areas. During the past 15 years, considerable public interest has arisen about the quality of the Nation's ground water resources. This is especially true for agricultural chemical residuals, which may potentially degrade ground water quality. Concern about agricultural sources of ground water contamination is driven by fears that exposure to agricultural chemicals in drinking water may pose human health risks.

The objective of this report was to use applied microeconomic models to evaluate the potential benefits of reducing or eliminating nitrates from drinking water. The more than 800 persons surveyed in 1994 lived in four regions: the White River area of Indiana, Central Nebraska, the Lower Susquehanna River Valley, and the Mid-Columbia Basin in Washington.

After being given a description of possible nitrate risks, and being asked to assume that their water supply contained nitrates above levels considered safe, respondents were asked if they would pay a randomly selected dollar amount for a water filter to lower nitrates to safe levels. Then they were asked if they would pay a higher dollar amount for a filter that would eliminate all nitrates from their drinking water.

Potential benefits for the 2.9 million households in the four study regions were estimated at $350 million, if households potentially at risk were protected from excessive nitrates in the drinking water.

Discovery of nitrates and pesticides in ground water during the late 1970's and early 1980's dispelled the commonly held view that ground water was protected from these chemicals by layers of rock, soil, and clay. In 1990, the U.S. Environmental Protection Agency (EPA) released results from a survey showing that, while at least half of the Nation's drinking water wells contained detectable amounts of nitrate, only about 1.2 percent of community water systems and 2.4 percent of rural wells contained nitrates at levels higher than EPA recommendations (10 mg/liter).

The Environmental Working Group estimates that two million people drank water from systems that violated the EPA nitrate standard at least once between 1986 and 1995. An additional estimated 3.8 million people drank water from private wells with nitrate levels above the 10 mg/liter standard.

The extent to which drinking water contamination from agricultural chemicals poses a risk to human health is unclear. A well-documented nitrate contamination concern is infant methemoglobinemia, in which nitrates impair the ability of an infant's blood to carry oxygen. Nitrates in water and foods (such as hot dogs) have also been suggested as possible sources of cancer. However, the health risk of water containing traces of nitrates at levels below those that possibly endanger humans is poorly understood.

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Updated: June 16, 1997