Environmental Progress - Winter 1999

Nearly 90 Percent of State Water Supplies Meeting Standards

Most violations reflect failures to monitor, not unsafe water quality

Eighty-eight percent of the community water supplies in Illinois regulated by the Illinois Environmental Protection Agency were complying with all state and federal standards to protect public health during 1997.

The 1996 amendments to the Safe Drinking Water Act require the Illinois EPA to compile compliance data and make it available to the public. The first tally was released last June. It shows that during 1997 more than 92 percent of the people served by community water supplies in the state were being delivered water that met standards for maximum contaminant levels, treatment techniques, and health advisories, and had been adequately monitored for detection of contaminants.

In Illinois, community water supplies that serve more than 25 residents on a year-round basis are regulated by the Illinois EPA. The Illinois Department of Public Health oversees "transient non-community supplies" that serve different users (such as campgrounds or highway rest areas) and "non-transient non-community systems" that serve the same individuals (for instance day care centers, schools or factories) at least 60 days of the year. The Illinois EPA currently regulates 1,805 community water supplies while IDPH regulates 4,256. The records show that 1,592 of the 1,805 supplies under Illinois EPA jurisdiction had not exceeded state and federal drinking water standards.

Of the total 6,061 systems regulated by either the Illinois EPA or IDPH, 576 systems reported 3,702 violations during calendar year 1997.

Safety factors are built-in

The U.S.EPA determines standards for drinking water after extensive research and includes significant built-in safety factors. Presently, community water supplies are required to monitor for 85 parameters. Failure to monitor is itself a violation, and the majority of the violations during 1997 fell into this category. The figures show that 63 systems had a total of 2,810 monitoring violations, while 152 of the total number of systems had 272 actual violations of the various standards, known as maximum contaminant levels or MCLs.

In monitoring required under the Total Coliform Rule, 114 systems had 135 violations, while 315 systems had a total of 491 violations of the monitoring requirement. Five systems had one treatment technique violation each under the Surface Water Treatment Rule that requires filtration and disinfection, or five violations statewide during the year, while six systems together had a total of 30 failures to monitor.

Under the Illinois EPA's performance agreement with U.S. EPA, the state has a goal of assuring that every Illinois public water system consistently provides water that is safe to drink. Standards are set for both short term and long term health effects. More than 98 percent of the population served by Illinois community water supplies received drinking water meeting the short term health standards. More than 94 percent received water that complied with the long term health standards.

Most violations are brief and corrected promptly

It is important to note that most non-compliance incidents were of short duration and prompt corrective action by the water supplies kept potential health risks at a minimum.

Lead and copper levels are monitored differently from substances with MCLs. Samples are collected at the taps in users' homes, with the number of samples required determined by the overall size of the population served; larger supplies must take more samples than small supplies serving fewer customers.

If more than 10 percent of the samples collected from taps exceeds 15 parts per billion of lead, the water supply must implement treatment or take steps to ensure lead is controlled. During 1997, a total of 1,717 community water supplies, or approximately 95 percent serving about 96 percent of the population, were below the 15 parts per billion action level.

Copies of the summary or complete annual water system compliance reports can be obtained by contacting the Illinois EPA's Division of Public Water Supplies, #13, P.O. Box 9276, Springfield, IL 62794-9276.