Officials Determine No Health Threat from Sewage Leak into Drinking Water Source

A clogged manhole in Waltham released approximately 900 gallons per hour of raw sewage Tuesday, some of which flowed into the Hobbs Brook Reservoir, a source of drinking water for the Cambridge community. City and state officials, however, emphasized that the leak does not pose a threat to public health.

Due to the size of the reservoir and the fact that the water goes through several stages of treatment, officials said, the leakage is of little concern.

“It is in the nature of any outdoor body of surface water that there are plenty of bacteria,” said Sam Lipson of the Cambridge Public Health Department. “There are plenty of animals that use those ponds, and there are humans as well.”

“This does not constitute even an event of minor concern for us,” he added.

Cambridge city officials were notified Tuesday morning by the city of Waltham that a blockage located about 400 feet from the reservoir caused backed up sewage to overflow and run into the reservoir. Despite initial difficulties locating the source of the leak due to the heavy snowfall recently experienced in the region, city workers removed the blockage by Tuesday afternoon, Cambridge City Manager Richard C. Rossi said.

According to the Cambridge Water Department, the maximum capacity of freshwater held in the Hobbs Brook Reservoir is 2.5 billion gallons. Both  Massachusetts Department of Environmental Protection spokesperson Edmund J. Coletta and Rossi emphasized that due to the size of the reservoir, citizens should not be concerned about the safety of the drinking water.

“We felt that the dilution factor was such that [the sewage] would not present any harm to the general public,” Rossi said.

Both officials added that in addition to the size of the Hobbs Brook Reservoir, the sewage would be further diluted and removed from the system by passing through other reservoirs and undergoing a treatment process.

Rossi emphasized that this mixing of different water sources as well as the treatment process mitigated any cause for health concerns.

The city evaluates the city’s water quality on a weekly basis, according to Lipson.

—Staff writer Samuel E. Liu can be reached at samuel.liu@thecrimson.com. Follow him on Twitter @samuelliu96.