Volume 43 Number 2
Demographics of Water Consumption
Consumers need better assurances that the water they're supplied isn't tainted with disease-causing contaminants. According to a survey by the Water Quality Association, more than 50 percent of Americans worry about impurities in their tap water. This isn't surprising since the Center for Disease Control (CDC) estimates that 1 million people in the United States become sick each year from consuming contaminated water.
During a 1994 meeting of the American Academy of Microbiology, it was projected that "water treatment technologies, if adequate, are often not applied, are poorly applied, or are not sufficiently monitored and controlled. Inadequate, interrupted or intermittent treatment has repeatedly been associated with waterborne disease outbreaks."1 This statement reflects that even the best available technology for water treatment is plagued by failures in the system or improper regulation, monitoring and control. The U.S. Environmental Protection Agency (USEPA) Science Advisory Board concluded in 1990 that drinking water contamination is one of the highest environmental risks to human health.3
-- The population served by community water systems in violation of health-based requirements will be reduced to 5 percent (compared to 19 percent in 1994).
-- Every person served by a public water system that draws from an inadequately protected river, lake or reservoir will receive drinking water that's adequately filtered -- 393 systems serving 9.9 million people didn't meet all Surface Water Treatment Rule (SWTR) requirements for having filtration treatment in place for surface waters as of 1995.
-- Ninety percent of the nation's river and stream miles and lake and reservoir acres designated as drinking water supplies will provide water that's safe to use after conventional treatment as compared to 84 percent deemed safe in 1994.
-- Sixty percent of the population served by community water systems will receive their water from systems with source water protection programs in place (compared to only 5 percent of the population in 1993).
A status report on the USEPA's progress in achieving these goals by 2005 is not currently available. And regardless of the improvements in a water system's ability to treat and provide safe drinking water to consumers, the quality of water supplied is only as good as the quality of its subsequent distribution system. Deteriorated distribution piping allows water to become contaminated in the distribution system. According to a 1997 USEPA report to Congress, significant upgrades and repairs are needed throughout the country (see WC&P, "U.S. Water Infrastructure Needs," August 1999, p. 76)
Consumer water demands
How much water do individuals consume each day? Figure 2 indicates the average tap water intake rates for each age group.4 Infants between the ages of 0-1 consume an average of 302 milliliters (ml) of water per day. Although they consume less water than adults, the effect of contaminants may be more severe due to their small size and under-developed immune systems. The average tap water intake rate increases as individuals age. Persons over 65 drink an average of 1,459 ml per day. This value is slightly less than the value of 2,000 ml -- 2 L -- used by the USEPA to determine risk assessment. Yes, actual consumption is 27 percent less than the USEPA's figure to calculate risk. Thus, the agency may be overestimating risk in some cases for two reasons: 1) an average is just that and some people may actually consume more, and 2) increasing the value of tap water consumption provides a slight margin of safety for risk analysis. On the other hand, exposure to water in foods and from sources other than the tap also adds to the value of total water consumed per day.
Ground vs. surface water
Recent studies by the USEPA indicate that a substantial number of groundwater sources show evidence of fecal contamination. The primary source of groundwater contamination has been listed as septic tanks that serve 25 percent of the U.S. population. Figure 5 shows the percentage of ground water source systems citing water contamination sources.
Developing contaminant rules
An initial broad list of more than 300 suspected contaminants was narrowed to a list of 60 priority contaminants. Each contaminant is divided into categories of need for regulatory determinations, research and occurrence. The USEPA will select at least five contaminants from the Regulatory Determination category and determine, by August 2001, if there's a need for their regulation based on whether a meaningful opportunity is likely to reduce health risk. If deemed necessary, a regulation may not be promulgated until February 2005.
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