UNIVERSITY WATER SYSTEM Has Levels of Total Trihalomethanes (TTHM)
Above Drinking Water Standards

The University of Iowa recently received notice that its water system violated a drinking water standard. Although this is not an emergency, as our customers, you have a right to know what happened, what you should do, and what we are doing to correct this situation.
We routinely monitor for the presence of drinking water contaminants. Testing results we received on February 1, 2017, show that our system exceeds the standard, or maximum, contaminant level (MCL), for total trihalomethanes. The standard for total trihalomethanes is 0.080 mg/L. The average level of total trihalomethanes over the last year in our system was 0.081 to 0.110 mg/L.

What should I do?

  • You do not need to use an alternative (e.g., bottled) water supply. Disease prevention specialists with University of Iowa Hospitals and Clinics say special precautions are not necessary. However, if you have specific health concerns, consult your doctor.

What does this mean?
This is not an immediate risk. 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 system, and may have an increased risk of getting cancer.

What happened? What is being done?
Trihalomethanes are a byproduct of the water treatment process that form when chlorine, added to the water during the treatment process for disinfection, reacts with naturally occurring organic matter in the water. Above normal winter temperatures have increased the amount of naturally occurring organic material in the Iowa River, resulting in the need for additional chlorination. The additional chlorine used to make the water safe to drink leads to higher TTHM levels.

In October of 2015, the UI requested permission from the Board of Regents, State of Iowa, to proceed with project planning for a reverse osmosis filtration system to address high nitrate levels in the Iowa River. This system, which will also reduce the organic matter that causes the formation of TTHM's, is in the design phase for installation and is expected to be on-line in the next 18 months.

In the short term, flushing of fire hydrants will be performed to lower the residence time of water in the distribution system, reducing the amount of time available for TTHM's to form.
Please be aware, however, that the level of TTHM's in the water is calculated based on quarterly samples over the previous 12 months. There is a possibility that even with reduced TTHM levels, the 12-month average may remain at or above the MCL until enough quarterly samples have been taken to lower the average.

For more information, please contact:

Wendy Moorehead, UI Facilities Management

This notice is being sent to you by UNIVERSITY WATER SYSTEM, PWSID #5225101
Date distributed:2/9/2017