Important Information About Your Drinking Water (DMWW customers in Runnells and Southeast Polk, south of I-80)

Friday, March 28, 2014

IMPORTANT INFORMATION ABOUT YOUR DRINKING WATER

Southeast Polk Rural Water District has levels of Total Trihalomethanes (TTHM) Above Drinking Water Standards

Our water system recently 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 the situation.

We routinely monitor for the presence of drinking water contaminants. Testing results we received on March 21, 2014, show that our system exceeds the standard, or maximum contaminant level (MCL), for Total Trihalomethanes (TTHM). The standard for Total Trihalomethanes (TTHM) is 0.080 MG/L. The average level of Total Trihalomethanes (TTHM) over the last year was 0.0926 MG/L.

What should I do?

You do not need to use an alternative (e.g. bottled) water supply. 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 systems, and may have an increased risk of getting cancer.

What happened? What is being done?

Trihalomethanes are one of the most common disinfection by-products. Disinfection by-products form when chlorine used for disinfection reacts with organic matter present in the water.

During the first quarter of 2014, Des Moines Water Works saw elevated levels of ammonia and Total Organic Carbon in both the Des Moines and Raccoon Rivers. Disinfection with chlorine is more difficult when ammonia is present in source waters. Ammonia consumes chlorine, leaving it unavailable for disinfection against bacteria, viruses, and other disease-causing organisms. This requires additional chlorine to eliminate the ammonia and obtain proper disinfection during the final stage of treatment. For that reason, chlorine levels have been purposefully higher since early January. Elevated levels of Total Organic Carbon, at a time when chlorine is being dosed aggressively, enables the formation of the undesirable disinfection by-products.

This is not the first notice for this public water supply in regard to this issue. Similar notices were sent in 2013 following measurements in 2012. As a result of those measurements and notices, Des Moines Water Works’ 2014 Capital Improvement Plan includes the design and installation of a disinfection by-product reduction system in the primary water storage tank within the public water supply system.

The regulation requires averaging the samples obtained in the last four calendar quarters. Because of the high results in the first quarter in 2014, similar notices will be sent to customers in future quarters unless and until the average falls below the standard. Customers can expect three additional notices in 2014.

For more information, please contact Des Moines Water Works Customer Service by any of the following means:

Phone: (515) 283-8700
Mail: 2201 George Flagg Parkway, Des Moines, IA, 50321-1190
E-mail: customerservice@dmww.com

Please share this information with all the other people who drink this water, especially those who may not have received this notice directly (for example, people in apartments, nursing homes, schools, and businesses). You can do this by posting this notice in a public place or distributing copies by hand or mail.

This notice is being sent to you by Des Moines Water Works on behalf of Southeast Polk Rural Water District. PWSID #: 7774701. Date distributed: March 28, 2014.