TEWKSBURY — Residents received a notice last week from the Tewksbury Water Department informing them of a violation received from the Massachusetts Department of Environmental Protection.
According to Scott Brinch, Assistant Director of Utilities for Tewksbury, the water department’s testing of the town’s water supply revealed a higher-than-normal level of TTHMs, trihalomethanes, a byproduct of the disinfection process. Tewksbury samples its water at multiple locations on a consistent basis in order to monitor the town’s drinking water supply.
Brinch explained that the town’s samples are averaged on a quarterly basis for the DEP and conditions in the source water for Tewksbury, the Merrimack River, have contributed to the issue.
“There is more organic material than usual in the river,” said Brinch, noting that other communities who also rely on surface water for their drinking water supplies have experienced this issue.
Extreme weather conditions this summer are factors.
“The Total Organic Compounds in the Merrimack are at the highest level anyone can remember,” said Brinch.
Brinch explained that TTHMs are formed when chlorine, which is added to drinking water to combat bacteria, combines with organic material in water over time.
“We have a lot of water in our system,” said Brinch, referring to the three water holding tanks in Tewksbury, as well as the extensive water in the underground pipe delivery system.
When water sits for a period of time, TTHMs can form. TTHMs are made up of volatile organic compounds. It would take many years of exposure to TTHMs at a higher than recommended level to potentially cause an issue.
Issuance of the notice is required by the EPA, and is a standard procedure, according to Brinch. He did explain that this is not akin to a boil water order or immediate health threat. It will take time to work through the water in the system for the testing to show normal levels.
Several heat waves and significant rain this season have contributed to excessive growth of plant material in the Merrimack River. Other material in the water includes silt, clay, detritus (decomposing matter such as dead animals), and other solids.
For perspective, TTHMs are present in swimming pools, bottled water that comes from a municipal source, commercial products that use water in their production, dairy products, and through inhalation, according to the World Health Organization.
TTHMs are naturally occurring compounds that form when chlorine is used for disinfection in water. The chlorine reacts with the organic compounds to form TTHMs over time. It is a challenge; the chlorine is needed to disinfect the water, but over time, the chlorine binds with the naturally occurring components in water to create these additional compounds.
The water treatment plant at Merrimack Drive has the highest rating for water purification given, so residents should feel confident in their drinking water supply. The plant has multiple phases of water treatment starting with powder activated carbon to pre-treat the source water, granular carbon which traps solids, and aeration blowers which strip the TTHMs out of the water.
Brinch said that the town is also in the middle of its annual flushing program which will help move more water through the system.
“We have a lot of water underground,” said Brinch, and moving the water helps keep it fresh.
The water department is working on adjusting its chlorine formula to see if it can reduce levels further.
“It’s a delicate balance,” said Brinch.
Brinch encourages anyone who is concerned or has questions to call town chemist Melissa Woodbury at 978-858-0345.