Since the beginning of August, people in the western area of Washington Suburban Sanitary Commission (WSSC) water system have noticed brown or yellow discolored water. Last week WSSC held a news conference on the banks of the Potomac River, the source of drinking water for the majority of WSSC’s 1.8 million customers, to explain the cause of the brown water and reassure customers that the water is safe to drink. However, WSSC advises that the discolored water should not be used to wash laundry; and WSSC believes the discolored water may persist for several more weeks. The Washington Aqueduct and Fairfax Water are not having difficulty delivering safe and clear water to their customers.
At the press conference WSSC General Manager Carla A. Reid , WSSC’s Director of Production J.C. Langley, Deputy Heath Officer for the Montgomery County Department of Health and Human Services Mark Hodge, and “WSSC water quality experts” outlined the cause of the discolored water customers were receiving in Montgomery and Prince George’s counties. According to their press release
and streamed news conference, for the past few weeks there has been an increase in organic material in the Potomac River, possibly caused by recent severe rain storms. Organic material comes from decayed leaves, tree debris and vegetation that are washed into the river.
During the treatment process, WSSC uses chlorine to not only disinfect the water , but also as an oxidizing agent. The chlorine controls manganese and other contaminants levels to make the water both clear and safe for drinking. Manganese is a natural mineral also found in waterways and groundwater. The problem is that chlorine is a very good oxidizing agent and also interacts with natural organic matter present in rivers and streams to form what are called disinfection by-products that increase the incidence of cancer.
The Environmental Protection Agency (EPA) regulates 11 of the disinfection by products that are formed when chlorine reacts with naturally occurring organic matter and that have been positively linked to health impacts. The EPA established maximum contaminant levels for these 11 disinfection by products: four trihalomethanes (THMs), five haloacetic acids (HAAs), bromate, and chlorite in order to protect public health.
The rule making and implementation for these Disinfectants and Disinfection Byproducts Rules , part of the group of Microbial and Disinfection Byproducts Rules took place between 1998 and 2006. Part of the Safe Drinking Water Act, these rules are a series of interrelated regulations that address risks from microbial pathogens and disinfectants/disinfection byproducts. In reaction to these rules,
many water utilities changed their method of disinfection to comply with EPA limits on disinfection by-products. This resulted in many water utilities moving away from chlorine disinfection to alternatives such as chloramine, chlorine dioxide, and ozone. WSSC stayed with chlorine as their primary disinfectant.
With an increase in organic matter, WSSC had to cut the amount of chlorine they were using to meet the limits of the Disinfection Byproducts Rules. Excess disinfection by products in the system would require the WSSC to stop delivering water. However, the brown water is “safe.” Manganese is not a health hazard and is not regulated by the EPA as a drinking water contaminant. EPA considers manganese a secondary contaminant for aesthetic reasons only. The EPA level for manganese, for aesthetic purposes, is 0.05 mg/l. WSSC’s current manganese levels are around 0.01 mg/l to 0.02 mg/l. Although below EPA’s aesthetic level, it can still cause discoloration.
At the news conference WSSC emphasized that they performs more than 100 water quality tests every day, and all current test results indicate that the water is safe to drink. WSSC does warn that the discolored water should not be used to wash laundry as the staining it causes is permanent. The presence of manganese in a water supply can lead to a buildup of in pipelines, household water pipes, water heaters, and water softeners (though water softeners can remove some manganese it is not their primary purpose and there are better and cheaper in-home systems to treat water for excess manganese).
Last winter WSSC experienced discolored water reportedly caused by excessive road salt. I assume they made adjustments to hold a primary drinking water standard within EPA limits. Now excessive organic matter has caused this episode. The similarity here is that WSSC has not been able to effectively treat the variations in the Potomac River throughout the year. No amount of explanation will make it all right that WSSC cannot consistently deliver safe, clean, clear, and good tasting water twelve months a year. First world nations can deliver safe and clear water 24/7 throughout the year. Nothing less is acceptable.
Manganese can cause a variety of nuisance problems, affecting both the taste and color of the water and food prepared with the water. Manganese may react with the tannins in tea, coffee and some alcoholic beverages to produce a black sludge, which will affect both taste and appearance. Manganese will cause brown staining of laundry, porcelain, dishes, utensils and glassware. These stains are generally not easily removed by soaps and detergents; in fact, using chlorine bleach and alkaline cleaners (such as sodium and carbonate) may intensify the stains. You might want to consider installing an oxidizing water filer (sometimes called an iron or greensand filter) in you water supply line to remove the manganese.
The Washington Aqueduct and Fairfax water use chloramine and are not experiencing these problems. As the WSSC always states at the bottom of their press releases: Established in 1918, today WSSC is among the largest water and wastewater utilities in the nation.