Chelsea Community Letter 2023

CITY OF CHELSEA, MA
DEPARTMENT OF PUBLIC WORKS
CITY HALL, 500 BROADWAY, ROOM 310, CHELSEA, MA 02150 

PHONE: 617-466-4200 •  FAX: 617-466-4210

Public Water Supply # 3057000

The Chelsea Water and Sewer Department is pleased to provide this annual water quality report to keep you informed about your water system. 
 

Water Distribution System

The City of Chelsea purchases all of its water directly from the Massachusetts Water Resources Authority (MWRA). The MWRA delivers the water to Chelsea’s distribution system through five MWRA master meters. Chelsea’s distribution system then delivers the water to homes, businesses, schools, and other facilities for drinking, fire protection and other uses. Chelsea’s water distribution system comprises approximately 56 miles of water mains, ranging in size from 6 to 20 inches in diameter, approximately 575 fire hydrants, over 1000 mainline gate valves, and in excess of 5,100 service shutoff valves (“curb stops”). Upwards of 70% of the water mains in Chelsea’s distribution system are over 50 years old, and an estimated 47% of the water mains are old unlined cast iron pipe. Unlined pipe allows tuberculation (rust) to grow on the inside surfaces of the pipe. While not a health problem, tuberculation restricts the amount of water conveyed by the pipes during firefighting operations, and can give the water a rusty or yellow/red appearance. These older mains are also more likely to break and require emergency repair. 
 

Water Quality

Chelsea monitors the water quality in our distribution system at 13 sites every week. These sites are tested for temperature, chlorine residual and coliform bacteria. Coliforms are bacteria that are naturally present in the environment and are used as an indicator that other, potentially harmful, waterborne pathogens may be present or that a potential pathway exists through which contamination may enter the drinking water distribution system.  No more than 5% of samples can be positive in any month. Total coliform bacteria were found in the water in September 2023, and a Level 1 Assessment of the water was required.  A Level 1 Assessment is a study of the water system to identify potential problems and determine (if possible) why total coliform bacteria have been found in our water system. The Water Department responded by flushing water lines, sampling additional sites, and inspecting for any sources of contamination in the affected areas until positive coliform detection ceased. The problem was traced to low chlorine residuals in the water. For information regarding Chelsea’s weekly water quality and bacterial sampling results, click here.
 

Water System Improvements

Improvements to the Willow St., Watts St., and Central Ave. distribution area were completed in 2023. This work successfully replaced outdated cast iron mains with larger and modernized concrete lined ductile iron mains, providing improved quality and flow. This also allowed for the replacement of lead services with copper along the stretch, in line with the City’s total lead replacement program. The Downtown Broadway project to replace 760 feet of 12-inch water main, 450 feet of 8-inch water main, 60 feet of 16-inch water main along with replacement of 850 feet of lead service lines went to bid in fall 2023. The City has contracted for continued lead service line replacement in 2024 and work is anticipated to begin in the spring. Work continues to identify areas of low pressure and to update infrastructure in those areas to ensure improved water quality across Chelsea. 

Lead in Drinking Water 

The water in Chelsea’s mains is lead-free; however, lead can leach into the water from old lead pipes or pipes with lead solder, or  a lead service line (the water service pipe connecting the building to the city water main in the street). Twenty residences and two schools are sampled annually to ensure lead does not exceed EPA action levels. In 2023, Chelsea’s testing indicated we were below the lead Action Level of 15 parts per billion (ppb). The 90th percentile result for homes in Chelsea was 8.29 ppb. We also sampled for copper and results were below the copper Action Level of 1300 ppb with a 90th percentile of 128 ppb.