News Release: Level of trihalomethanes in Columbia water increases

Friday, May 2, 2008 | 11:12 a.m. CDT; updated 8:10 a.m. CDT, Tuesday, July 22, 2008

(Columbia, MO) -- For more than three decades, Columbia’s water met or exceeded all standards set by the Environmental Protection Agency. Columbia’s water is tested more frequently and more thoroughly than is required by law. More than 4,000 tests are run each year on samples from 39 locations throughout Columbia. Through this testing the utility staff became aware of a problem and is working to ensure that Columbia’s water continues to be a high quality resource for the community.

In 2007, Columbia’s water exceeded the maximum contaminant level for total trihalomethanes (TTHM). The average reported concentration for 2007 is 0.0823 milligrams per liter. The maximum contaminant level for total trihalomethanes is 0.08 milligrams per liter. In 2001, the Environmental Protection Agency lowered the maximum contaminant level from 0.1 milligrams per liter to 0.08 milligrams per liter.

There is not an immediate danger in consuming Columbia’s water. Trihalomethanes are a by-product of the disinfection process. They are formed when chlorine breaks down organic material in the water. Organic materials in the water can come from natural materials in the environment.

Chlorine is added to the water to kill bacteria, viruses and other organisms that could cause serious waterborne illnesses and death.

Trihalomethanes present problems over a long period of time. The city of Columbia is working with the Missouri Department of Natural Resources and the University of Missouri to find a solution to the problem and lower the levels of trihalomethanes.

Long-term exposure to levels of trihalomethanes that meet the maximum contaminant level is a health concern. A person consuming two liters of water per day for over 70 years could result in three to four cancers per 10,000 people, according to the Missouri Department of Natural Resources. The Environmental Protection Agency reports that people drinking water exceeding the standards for trihalomethanes might also experience problems with their liver, kidneys or central nervous system.

The city of Columbia has been working with the Missouri Department of Natural Resources to lower the level of trihalomethanes in our water supply. The city is entering into an agreement with the University of Missouri’s Water Resources Research Center to identify and correct any problems. The University’s research will take several months and the Missouri Department of Natural Resources will have to approve any changes to the treatment process. Possible solutions will be presented to the Columbia City Council and action will be taken.

Columbia Water & Light noticed that the levels of trihalomethanes were rising from the previous year’s average level of 0.0704 milligrams per liter at the end of 2007 and contacted the Missouri Department of Natural Resources. As was recommended, the amount of chlorine added at the treatment plant was lowered to reduce the formation of trihalomethanes. Chlorine cannot be completely eliminated at this time due to the risk of other waterborne illnesses forming. The city will continue to work under the supervision of the Missouri Department of Natural Resources to discover the cause and determine a solution to lower the level of trihalomethanes.

The Missouri Department of Natural Resources requires that the city of Columbia send a letter to all water customers outlining the information listed above. The letters are expected to be delivered to the post office on May 7.

This information is also on the city of Columbia’s Web site at Customers can contact Columbia Water and Light by sending an e-mail to or by calling (573) 874-7325. The Missouri Department of Natural Resources Northeast Regional Office can also be contacted for more information at (660) 385-8000.

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