But an estimated 1. Americans fall ill each year from drinking water contaminated with parasites, bacteria or viruses, according to a study published last year in the scientific journal Reviews of Environmental Contamination and Toxicology. That figure does not include illnesses caused by other chemicals and toxins. In the nations largest dairy states, like Wisconsin and California, farmers have sprayed liquefied animal feces onto fields, where it has seeped into wells, causing severe infections. Tap water in parts of the Farm Belt, including cities in Illinois, Kansas, Missouri and Indiana, has contained pesticides at concentrations that some scientists have linked to birth defects and fertility problems. In parts of New York, Rhode Island, Ohio, California and other states where sewer systems cannot accommodate heavy rains, untreated human waste has flowed into rivers and washed onto beaches. Drinking water in parts of New Jersey, New York, Arizona and Massachusetts shows some of the highest concentrations of tetrachloroethylene, a dry cleaning solvent that has been linked to kidney damage and cancer. Specific types of water pollution across the United States will be examined in future Times articles. Photo. Jennifer Hall Massey relies on drinking water that is brought in by truck and stored in barrels on her porch near Charleston, W. Va. Credit. Damon WinterThe New York Times The Timess research also shows that last year, 4. Safe Drinking Water Act at least once, according to an analysis of E. P. A. data. Those violations ranged from failing to maintain proper paperwork to allowing carcinogens into tap water. More than 2. 3 million people received drinking water from municipal systems that violated a health based standard. In some cases, people got sick right away. In other situations, pollutants like chemicals, inorganic toxins and heavy metals can accumulate in the body for years or decades before they cause problems. Some of the most frequently detected contaminants have been linked to cancer, birth defects and neurological disorders. Records analyzed by The Times indicate that the Clean Water Act has been violated more than 5. Companies sometimes test what they are dumping only once a quarter, so the actual number of days when they broke the law is often far higher. And some companies illegally avoid reporting their emissions, say officials, so infractions go unrecorded. Environmental groups say the number of Clean Water Act violations has increased significantly in the last decade. Comprehensive data go back only five years but show that the number of facilities violating the Clean Water Act grew more than 1. Day Clean' title='1 Day Clean' />Polluters include small companies, like gas stations, dry cleaners, shopping malls and the Friendly Acres Mobile Home Park in Laporte, Ind., which acknowledged to regulators that it had dumped human waste into a nearby river for three years. They also include large operations, like chemical factories, power plants, sewage treatment centers and one of the biggest zinc smelters, the Horsehead Corporation of Pennsylvania, which has dumped illegal concentrations of copper, lead, zinc, chlorine and selenium into the Ohio River. Those chemicals can contribute to mental retardation and cancer. Some violations are relatively minor. But about 6. 0 percent of the polluters were deemed in significant noncompliance meaning their violations were the most serious kind, like dumping cancer causing chemicals or failing to measure or report when they pollute. Finally, the Timess research shows that fewer than 3 percent of Clean Water Act violations resulted in fines or other significant punishments by state officials. And the E. P. A. has often declined to prosecute polluters or force states to strengthen their enforcement by threatening to withhold federal money or take away powers the agency has delegated to state officials. Neither Friendly Acres Mobile Home Park nor Horsehead, for instance, was fined for Clean Water Act violations in the last eight years. A representative of Friendly Acres declined to comment. Indiana officials say they are investigating the mobile home park. A representative of Horsehead said the company had taken steps to control pollution and was negotiating with regulators to clean up its emissions. Numerous state and federal lawmakers said they were unaware that pollution was so widespread. I dont think anyone realized how bad things have become, said Representative James L. Oberstar, a Minnesota Democrat, when told of The Timess findings. Mr. Oberstar is chairman of the House Transportation and Infrastructure Committee, which has jurisdiction over many water quality issues. The E. P. A. and states have completely dropped the ball, he said. Without oversight and enforcement, companies will use our lakes and rivers as dumping grounds and thats exactly what is apparently going on. The E. P. A. administrator, Ms.