GREAT BARRINGTON — The cause of discolored tap water that long has plagued Housatonic appears to be manganese that enters at the water source, not iron from old mains.
And levels of the naturally occurring mineral are far below those that can cause health problems, according to a new study commissioned by the Housatonic Water Works Co.
Cornwell Engineering Group, a Virginia-based consultant, also said in its Oct. 29 report that it recommends more investigation and monitoring of household plumbing that can leach copper and lead. Copper levels apparently were high in samples taken from some homes.
The waterworks will hold a public information meeting at 6 p.m. Thursday, via Zoom, with an engineer from Cornwell to answer questions and discuss the report and possible solutions, according to a letter sent to the company’s customers and posted to its website.
The findings are a new twist in an ongoing crisis for the waterworks and its customers, who endure bouts of water ranging from yellow to the color of dark tea. The discoloration happens during and after hydrant flushing, and amid warm summer temperatures. While not considered a health risk, residents remain wary.
The problem stretches back several decades, according to some water customers, but appears to have worsened in the past few years. The company maintains just under 850 household connections.
The discoloration was thought to stem from rust sediment churned up from old cast-iron mains.
While solutions still are unclear, solving the iron problem ultimately would involve replacing most of the system’s 17 miles of pipes.
It would take many years and $22 million, according to another consultant hired to evaluate the situation after several years of tempestuous public meetings in which customers demanded a fix.
This led the Select Board to consider a town takeover of the water company.
Solutions might look different now. Cornwell found that manganese concentrations are 0.086 milligrams per liter at the point of entry. The federal Environmental Protection Agency’s limit of 0.05 mg/L is when staining of laundry and other fixtures happens.
It takes 10 times that limit to be considered a health risk, according to the EPA. Excessive manganese can target the nervous system; and most exposure is through food, according to a 2004 agency report, with any problems apparently related to industrial jobs.
“Many of the reports of adverse effects from manganese exposures in humans are from inhalation exposures in occupational settings,” the report says.
James Mercer, treasurer and part owner of the waterworks, said that the new data is from three months of testing and analysis since early July, and that more is needed. The company hasn’t yet consulted about it with the state Department of Environmental Protection.
He said that while the new results are “surprising,” the problem is “primarily cosmetic,” as it was when it was linked to cast-iron pipes.
“It’s just like iron; it’s not a health hazard,” he said.
Cornwell recommends that the mineral be removed from water at the treatment plant at Long Pond, the source. The consultant also says that polyphosphates to separate the manganese shouldn’t be added to the water because they can corrode lead and copper in household systems.
Mercer said it’s too early to know the scope or cost of such a removal project.
Other recommendations from Cornwell include more sampling of water at the source and at homes during discoloration periods, to ruleout other causes.