WSSC explains cause of water discoloration

WSSC has issued an update regarding the ongoing discolored water situation affecting Montgomery and Prince George’s Counties.

“Our number one goal is public health and I want all our customers to know that WSSC water is safe,” said WSSC General Manager and CEO Carla Reid at a press conference yesterday. “But from an aesthetic standpoint, the water is unacceptable and I sincerely apologize to our customers impacted by this discolored water. Our customers should not have to think twice about their drinking water when they turn on their taps.”

“We will always make decisions that are in the interest of public health and safety,” said WSSC’s Director of Production J.C. Langley. “From a public health standpoint, it is more important to address the naturally-occurring organic material to reduce disinfection byproducts in the water versus the aesthetic issue of manganese. Unfortunately, that means the aesthetic issue of manganese will be around for the next several weeks until river conditions change.”

According to the press release:

Since the beginning of August, WSSC has received more than 700 discolored water complaints – a sharp increase from the 200 to 300 complaints each month during the spring. WSSC performs more than 100 water quality tests every day, and all current test results indicate that the water is safe.

In recent weeks, WSSC water quality experts have noticed an increase in organic material in the Potomac River, which occurs naturally in water, possibly caused by recent severe weather events. Organic material comes from decayed leaves, tree debris and vegetation. Manganese is a natural mineral also found in waterways. The increased levels of manganese in the treated water are causing the discoloration. During the treatment process, WSSC uses chlorine to disinfect the water and control manganese levels to make the water clear and safe for drinking. However, chlorine reacts with organic material to form disinfection byproducts – highly regulated drinking water contaminants by the U.S. Environmental Protection Agency (EPA). Disinfection byproducts are a public health concern. With an increase in organic material this summer, WSSC slightly reduced the levels of chlorine to stay well below the EPA limit for disinfection byproducts. While enough chlorine is present to disinfect the water and kill bacteria, the slightly lower level allows manganese levels to increase in the finished water – causing the discoloration.

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.

Residents have taken to Twitter to express their concern at the water discoloration, despite WSSC’s assurances that the water is safe:

WSSC has also issued the following contact information for affected customers:


Is your water still discolored? Let us know in the comments.


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