Town of Winthrop Taking Proactive Steps to Maintain Water Quality Despite Lower Than Usual Chlorine Levels Across the Region

Interim Town Manager Terence Delehanty wishes to inform residents that the Town of Winthrop is taking several steps to monitor and address lower than usual chlorine levels in the water system.

Winthrop is one of many communities served by the Massachusetts Water Resources Authority (MWRA) that is experiencing lower than usual chlorine residuals in water this year, though no harmful bacteria have been detected in Winthrop's water.

The lower than usual chlorine levels are caused by high levels of reactive organic carbon in source water at the Wachusett Reservoir as a result of heavy rains over the summer. The elevated levels of reactive organic carbon in the source water creates more demand for chlorine in the water and causes the chlorine to decay more quickly, which leads to decreased levels of chlorine in local water systems like Winthrop's.

Lower than usual chlorine levels leave water systems susceptible to detection of total coliform bacteria in water samples, and can also create more suitable environments for harmful water-borne bacteria.

As a result, the MWRA is proactively transferring water from the Quabbin Reservoir to the Wachusett Reservoir to improve water quality, and also increasing chlorine levels in source water.

The MWRA is also recommending that water system managers take several proactive steps to monitor and improve chlorine levels in local water systems that get water from the MWRA.

Those steps include:

  • Monitoring chlorine residuals throughout the water system
  • In areas where residuals are low, performing gentle flushing of the system to increase residuals
  • Performing additional chlorine residual monitoring to identify areas where residuals are low, and to asses whether flushing the system is improving chlorine levels
  • Ensuring that when residuals are low, water systems with water storage tanks monitor chlorine residual levels when the water tanks are feeding into the larger system. If those residuals are low, systems are advised to increase cycling of tank water, or even to drain and refill the tanks to increase chlorine levels by freshening up the water.

The Town of Winthrop is taking all of the recommended steps to address the issue.

Flushing the water system and water stored in tanks helps increase chlorine residuals by ensuring the water is fresher.

When flushing is being conducted, tap water may become discolored as a result of iron buildup that is disturbed by high-pressure flow through underground pipes. The best way for residents to clear discolored water is to run high flow faucets, like bathtubs, for several minutes until the water clears.

"I want to emphasize that, despite close monitoring, no harmful bacteria have been detected in the Town of Winthrop's water supply," Interim Town Manager Delehanty said. "The Town of Winthrop intends to continue watching this issue closely, keeping residents informed and taking all recommended proactive steps to ensure our community's water quality remains at the highest levels."

For more information on chlorine residuals and why they are important to water quality, click here.