January 2, 2014
City Adjusting Water Filtration Process to Address Disinfection Byproduct Violations
An unusual spike in disinfection byproducts in the Memphis water supply has resulted in a second round of violations of the Missouri Safe Drinking Water Regulations. Customers of the municipal water supplier received notification last week of the issue.
"Although this is not an emergency, as our customers, the public has the right to know what happened, what they should do, and what we are doing to correct this situation," said Water Superintendent Stacy Alexander.
The September 30, 2013 testing results for the water source showed 64.88 parts per billion (PPB) running annual average for Total Haloacetic Acids, which was slightly above the 60 PPB limit. Total Trihalomethanes were at 82.85 PPB, which exceeded the 80 PPB limit.
Alexander noted that the third quarter violations were residual carryovers from the second quarter testing results as the results use a running annual average, meaning the second quarter highs were still factoring into the 12-month average. He stated that third quarter results, standing alone, were both below the regulated levels.
"Due to unusually high levels of organic carbons in the source water during the second quarter of 2013, we exceeded EPA standards," Alexander said.
He added that the city's treatment process is being adjusted to remove a larger number of these organic carbons before the treatment process begins.
The process is currently being reviewed to determine the ability to increase the amount of activated carbon that is added prior to the filtration process. Alexander noted that the City of Vandalia has experienced similar issues and has had success with this process.
Haloacetic acids and trihalomethanes typically form as the result of chlorine-based drinking water treatment processes. The two byproducts are created when naturally-occurring organic and inorganic materials in the water react with the disinfectants, chlorine and chloramine.
Compliance with the regulation is based on a system's average over the past four quarters, with 60 micrograms of haloacetic acid per liter of water and 80 micrograms per liter of trihalomethane being the maximum allowed.
DNR officials noted that drinking water systems that use surface water sources, such as lakes and reservoirs, are more likely to experience problems with disinfection byproducts than groundwater systems -- those that receive their source water from wells -- because there is a greater amount of organic material in surface water. The organic material reacts with the chlorine that is required to reduce the level of naturally occurring -- but potentially harmful -- bacteria in the source water.
During 2012, 15 other water systems in Missouri violated the state and federal standards for disinfection byproducts.
Field staff from the regional office have been working with the city's water system operators to adjust the water treatment process to continue to kill harmful bacteria and other microorganisms while better controlling the levels of byproducts such as haloacetic acids and trihalomethanes.
The maximum contaminant levels (MCLs) are based on long-term exposure of drinking two-liters of water every day for 70 years.
Haloacetic acids have low human and animal toxicity. The current level of haloacetic acids in Memphis's drinking water, while slightly above the state and federal drinking water standards, is not considered an immediate health concern. If a person were to drink water with elevated levels of haloacetic acids over a lifetime, they may have a slightly increased risk of developing certain types of cancer, including bladder, rectal, or colon cancers. Exposure to high levels of certain types of haloacetic acids has also been shown to cause adverse reproductive or developmental effects in laboratory animals.
The same can be said for trihalomethanes, as some people who drink water containing total trihalomethanes in excess of the MCL over many years could experience liver, kidney, or central nervous system problems and increased risk of cancer.
Officials indicated that Memphis residents do not need to use an alternative water supply, but those with specific related health concerns may wish to consult a physician.
For more information you can contact the city water department at 465-2013 or the Missouri Department of Natural resources' Northeast Regional Office at 660-385-8000 or the DNR Public Water Drinking Branch at 573-751-5331.