Many Americans thought tap water could make them ill only if they traveled to some Third World countries.
Then in April, thousands of Milwaukee-area residents came down with diarrhea, abdominal pains and vomiting. At first it was thought to be a flu outbreak. Laboratory tests eventually detected a waterborne parasite in the city's water supply, which comes from Lake Michigan.
By the time Milwaukee's water was declared safe again, an estimated 370,000 people had been made sick by drinking water contaminated with the parasite, cryptosporidium. Forty-seven died, some of them AIDS patients or others with compromised immune systems.
The incident, with pictures of people boiling water or lining up to buy bottled water, made news nationwide. And a report issued last week by a Washington-based environmental group warns that there could be more Milwaukees.
There is widespread contamination of drinking water nationwide, the Natural Resources Defense Council warned. In its 3,500-page report, "Think Before You Drink," the group charged that neither the states nor the federal government is doing enough to ensure the safety of our water.
"Capitalizing on consumer faith that tap water is invariably safe and secure in the knowledge that state and federal officials rarely hold systems accountable, many utilities have let water quality slide, sometimes at the expense of human health," said Erik D. Olson, an NRDC lawyer and the report's author.
And the NRDC named names, listing more than 250,000 violations of federal rules, where water systems either had occasional or chronic contamination or had failed to perform the required testing to ensure that their water was safe.
The contaminants found in community and private water systems ranged from bacteria, which could cause other flu-like outbreaks, to toxic chemicals such as arsenic and lead, which studies suggest could cause cancer and nerve damage. Especially troubling are trihalomethanes and other cancer-causing compounds that are produced, ironically enough, by the widespread use of chlorine in water systems to kill bacteria.
The report quickly drew testy rebuttals from officials who run community water systems and from state regulators overseeing drinking water safety.
A spokeswoman for the American Water Works Association, a utility industry group, charged that the NRDC had "hyped" the degree of water problems.
Likewise, a spokesman for Maryland's Department of the Environment contended that the NRDC's report contained errors and exaggerated the severity of water contamination in the state.
Baltimore City, for instance, was apparently wrongly accused in the report of failing to test enough for toxic lead and copper in the water supplied to 1.6 million people in the city and four surrounding counties. The NRDC's listing of violations in Maryland also lumped in a few from neighboring Delaware and Pennsylvania -- and even one from Georgia.
"I don't think anybody in the state of Maryland needs to be concerned about the quality of their drinking water," assured Michael Sullivan, the state spokesman.
Mr. Olson readily acknowledged that the water-violation data in his report may be flawed. But he blamed the mistakes on the Environmental Protection Agency, which supplied the information, and he contended that the errors simply proved one of the NRDC's points -- that neither state nor federal regulators are keeping a close watch on drinking water safety.
So, is our water safe to drink? Even environmentalists say it is, for the most part. Most water systems are complying with federal rules, Mr. Olson says, "and there is no need for panic."
Many of the contamination violations listed by the NRDC report, such as at Aberdeen Proving Ground and Patuxent Naval Air Station in Maryland, were one-time or occasional occurrences, which either were quickly fixed or were blamed on faulty testing.
But chronic contamination problems seem to hit poor, small communities worst. And even some large communities are relying on antiquated treatment systems that do not protect consumers from disease- or cancer-causing contaminants.
At the same time, local and state officials are pressing Congress to ease the burden of "unfunded federal mandates," and the Safe Drinking Water Act of 1974 is a prime target.
The EPA now has standards setting limits on 84 contaminants in drinking water, and the agency is considering tightening some of those limits and adding new ones for dozens of other substances.
"Some utilities complain they are having to test for things that never have been found there and probably never will be," notes Joan Dent, public information director for the water works association, based in Denver. "How important is this, and how much does the community want to spend?"
Noncompliance already is high. Ninety percent of the violations listed in the NRDC's report were for failures to test the water and report the results to state regulators.
In Maryland, where the NRDC report claimed that some 99,000 residents drink water that was at least occasionally contaminated, state officials say they have tried to help water system operators rather than fine them for such problems.
The state has spent more than $13 million in the past two years on water system improvements, including a brand new system for Lonaconing and four other small Allegany County communities that have been plagued by bad water. And the town of Hebron in Wicomico County is drilling new wells under state orders to remove nitrate contamination.
Meanwhile, environmentalists and health advocates are pressing the federal government to crack down on chlorination, which some studies indicate may be causing more than 10,000 cases of bladder and rectal cancer. Such chlorine-related contaminants can easily be filtered out using granular activated carbon, the NRDC says, and such treatment has recently been installed in Cincinnati for about $30 per year per customer.
But environmentalists and government officials alike acknowledge that communities need more money to comply with increasingly stringent testing and treatment requirements. In Maryland, the Schaefer administration has set up a revolving loan fund to help upgrade water systems, but it has no money. The administration has been rebuffed by the General Assembly in seeking funds and the ability to levy fines against violators.
The Clinton administration, meanwhile, has proposed an overhaul of the federal law, which would streamline and strengthen enforcement while giving communities more time to comply with new testing and treatment requirements. The administration has asked Congress for $4.6 billion over the next five years to help communities safeguard their water.
"Public water systems generally are very safe," explained Charles Fox, an EPA spokesman. "The issue, really, is how do we make it more safe, how do we improve protection of the public health?"
Timothy Wheeler covers the environment for The Baltimore Sun.