A problem at a water tower in La Salle’s east end has raised levels of a carcinogen, but the head of waterworks said the problem will be corrected before becoming a health threat.
Notices were mailed to city residents Monday reporting that March 18 test results showed water from the Cannon water tower, located behind JC Whitney on U.S. 6, exceeded the standard for total trihalomethanes. The standard for TTHMs is 0.080 milligrams per liter (mg/L) and La Salle’s March reading was 0.086.
(Editor’s note: The advisory is confusing and makes it look as if La Salle’s reading was 1,275 times higher than the threshold. It isn’t. The city was required to disclose a yearly average not to be confused with the March 18 reading.)
“This is not an immediate risk,” the advisory stated. “If it had been, you would have been notified immediately.
“However, some people who drink water containing trihalomethanes in excess of the MCL over many years may experience problems with their liver, kidneys, or central nervous systems, and may have an increased risk of getting cancer.”
Most residents are not affected. While advisories are required to be sent to all residents, the head of La Salle’s waterworks said Tuesday the water tower problem is limited to an area east of Enterprise Drive, across from La Salle Speedway.
Most water users there are industrial. Additionally, many of the households there draw from wells and also are unaffected.
Bradley Reese, superintendent of water works, said those households that draw from the water tower need not worry: Trihalomethanes pose only a long-term risk of cancer and the problem will be corrected within 90 days at the latest.
“The water is safe to drink,” Reese said. “It’s safe to use.”
A spokesman for the Illinois Department of Public Health agreed, insofar as the level reported by La Salle “only slightly exceeds” its 80 (parts per billion) maximum contaminant level, a threshold established by the U.S. EPA.
“For people who drink an average amount of water, there is no immediate cause for concern,” said Michael Claffey, public information officer for IDPH.
Trihalomethanes are a group of chemicals that form when drinking water is disinfected with chlorine. They include chloroform, bromoform, bromodichloromethane and dibromochloromethane. People can be exposed to these chemicals by drinking chlorinated water, or breathing vapors while bathing, showering, or swimming in a pool. Their combined concentrations are reported as total trihalomethanes, or TTHMs.
Reese said the problem occurred because water usage in the Cannon water tower is low during the winter months.
“The water gets older and as it ages the chlorine ages and when it ages it produces byproducts,” Reese explained. “Trihalomethanes is a byproduct and that can, over a very long period of time, cause cancer — but that’s not going to be a problem because we’re going to get it fixed.”
The solution, he said, is to install a new mixer that combines the reserve water with fresh water and so keeps any byproducts within an acceptable range. Reese said he hopes to have that done by the end of May. Installing a new mixer is not a minor job, however, so Reese disclosed a 90-day window in case of a delay or complication.
Once the work is completed, Reese said, the city will issue another notice saying the issue has been fixed but that monitoring will continue.
While the water is safe, Reese and Claffey said any affected residents seeking additional peace of mind can minimize their exposure by using bottled water or filtered water.
Reese said pitchers using charcoal cartridge filters are recommended over installing household charcoal filters, primarily because he doesn’t want homeowners to incur a costly improvement for a problem that will be fixed in a few weeks.
Claffey said filters should be NSF Certified and have a contaminant reduction claim for TTHMs. Search for NSF Certified products at https://info.nsf.org/Certified/DWTU/.