Almost 94% of Illinois Water Supplies Met Requirements in 2007

The majority of Illinois public water supplies met all state and federal health requirements during 2007, according to Illinois Environmental Protection Agency's Annual Compliance Report. The announcement was made June 26 in a press release.

The report, prepared as required by the federal Safe Drinking Water Act, reflects a significant improvement in compliance since 1995, when annual compliance reports were first required by the U.S. EPA. The data show that 93.9 percent of about 12 million people served by Illinois community water supplies received drinking water that met all health requirements.

"The Illinois EPA's goal is for every public water supply system to provide water that is consistently safe to drink, and these figures show we continue to make progress toward that goal," said Director Douglas Scott.

In Illinois, water suppliers providing drinking water to consumers are regulated either as community or non-community water supplies, based chiefly on the number of users they serve for specified periods of time. Community water supplies are regulated by the Illinois EPA. During 2007, there were 5,919 public water supplies in the state; 1,787 of them were defined as community water supplies falling under state regulation.

Campgrounds and highway rest stops, for instance, are considered non-community water supplies, as are day care centers, schools, and factories. These are regulated by the Illinois Department of Public Health. Non-community water supplies serve 504,980 persons.

During 2007, a total of 783 out of the 5,919 public water supplies in the state were shown to have violations of regulations. These 786 water systems accumulated a total of 6,676 violations. As in the past, most violations were monitoring/reporting violations (such as failure to collect samples or provide documentation), short in duration, and the public water supply returned to compliance by the next reporting period. The overall potential risk to public health was minimal. When a potential health risk was present, the public water system was required to issue public notification to all consumers.

U.S. EPA and the states evaluate compliance on the basis of both acute (short-term) and chronic (long-term) health requirements with standards that usually differ for the two categories. The latest Illinois EPA figures show that 99.9 percent of the population served by community water supplies received water that met all acute standards, and 94 percent received water that was in compliance with chronic requirements. Standards for acute requirements are usually stricter than chronic standards. For most contaminants, the latter is based on projected health risks from daily consumption of large amounts (approximately two liters) of water on a daily basis over an extended period of time.

In most cases, when contaminant levels exceed maximum allowable limits, treatment is required to be installed in the shortest amount of time taking into consideration the cost, health effects (acute vs. chronic), and size of the project. All of the public water supplies that had violations during 2007 have either returned to compliance, entered into an enforceable agreement and schedule to take whatever steps are needed to return to compliance, or are in the formal enforcement process involving the office of the Illinois Attorney General. Enforcement cases involving the office of the Illinois Attorney General could result in monetary penalties as well as the water supply being required to achieve compliance with the regulations.

For copies of the report, visit

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