Cambridge Water Supply Discolored by Manganese

Rising levels of manganese are causing the recent discoloration of the city's water supply, according to a City of Cambridge Water Department press statement issued last week.

Despite the yellow and brown discolorations, the water supply is safe for drinking, said Doreen A. DiVasta, assistant quality control supervisor for the Water Department.

"It's perfectly safe to drink," she told The Crimson in an interview yesterday.

Manganese, an oxidizing metallic element present in the soil, may stain laundry washed in the discolored water, the press release cautioned.

Although the discoloration is part of a normal seasonal cycle, the problem has been particularly pronounced this year, DiVasta said.

"This year it's been bad. It always happens this time of year, but this year is the worst it's been in 10 years," she said.

The Water Department will be using the compound potassium permanganate to treat the water supply, DiVasta said.

"[Potassium permanganate] will oxidize the manganese and the iron to precipitate out," DiVasta said. "Right now it's dissolved in the water, and you can't remove it, so it's just going through the system."

The Water Department expects to treat the water supply by the end of the week, once some necessary equipment arrives, she said.

DiVasta attributes increased levels of manganese and iron to seasonal changes which naturally occur in reservoirs during the fall.

Falling leaves, changing water temperatures and seasonal rains all contribute to changes in reservoir conditions, according to the city's statement.

"The fall leaves and the organic matter from the reservoir add color to the raw water in much the same way as a tea bag works when tea is brewed," stated the press release.