Is America's water safe to drink?

According to Perry L. McCarty, a sanitary engineer at Stanford University, a quarter of US drinking water is threatened by contamination. To this warning can be added the report of the congressional General Accounting Office (GAO) that 28 ,000 community water systems, 43 percent of the total, reported federal health standards violations in 1980.

America, it would seem, is becoming one of those countries where visitors wonder if they can drink the water.

Some of the problem, according to the GAO, is due to laxity on the part of water system operators in failing to test for ordinary kinds of contamination, let alone exotic chemical pollution. Even were that failing to be corrected, however, the US water supply would still be in trouble. The kind of contamination McCarty has in mind is the insidious spread of industrial chemical and pesticide pollution. He is especially concerned about its largely undetected infiltration of ground water.

In a statement issued by Stanford University, McCarty explains that sanitary engineers and water supply agencies had assumed that soils would trap a good deal of the pollution that enters them. Now, he says, it is known that many industrial solvents and pesticides just pass right on through the soils into underlying aquifers.

While he acknowledges that at present the main pollution problem is with rivers, he considers ground water pollution a rapidly growing danger which could become the dominant concern in the future. He explains that polluted rivers can often be cleaned up by closing off the pollution source. Ground water, on the other hand, is less able to cleanse itself. Pollutants can become trapped in aquifers. Moreover, testing ground water is difficult and costly. It involves sophisticated analysis and the drilling of deep wells.

The situation is further complicated by the fact that standards have not yet been established for drinking water concentrations of many of the chemicals. Thus, were traces of them to be found in water, officials would not know whether or not the water were safe. Moreover, the chemicals will not always impart a taste. Water that tastes fine may be dangerous, while some nasty-tasting water is safe to drink.

Given these uncertainties and the fact that the full extent of ground water contamination is not known, McCarty warns that no ground water can be considered safe until tested. Enough cases of contamination have already been found to make everyone cautious, he notes.

Here then is yet another dimension to America's pollution problem. It shows the importance of tight standards, not only for water supplies themselves but for the disposal of chemical wastes that can spread pollution in undetected ways. At this writing, the Environmental Protection Agency was rewriting its rules on such disposal to make them less stringent. Surely, considering the growing threat to US water supplies, any such relaxation would be foolish.