Total Trihalomethanes (TTHMs)

IMPORTANT INFORMATION ABOUT YOUR DRINKING WATER: To all customers of the Westminster Water Department located in Westminster, Massachusetts
TTHM Update

Total Trihalomethanes (TTHMs) are Above Drinking Water Standards 

This is an important notice - please translate it for anyone who does not understand English. 

This notice is to advise our customers that our water system is in noncompliance with the drinking water standards for Total Trihalomethanes (TTHMs).  Although this is not an emergency, as our customers, you have a right to know what happened, what you should do, and what we are doing to correct this situation. 

We are required to monitor the drinking water for TTHM levels on a quarterly basis (once every three months) at two specific locations in the distribution system. The sample results during the last quarter show that our system exceeded the standard or maximum contaminant level (MCL) for TTHMs at one out of two locations during the April through June 2022 compliance period. The standard for TTHMs is 80 parts per billion (ppb), and compliance is determined on a quarterly basis by averaging all samples collected at each location for the last 12 months (Running Annual Average). The locations and those averages are as follows (averages above the MCL have been highlighted): 

What does this mean? 

This is not an immediate risk.  If it had been, you would have been notified right away. However, pregnant women, infants, and women of childbearing age may be at increased risk and should seek advice from their health care providers if they have any concerns. Some people who drink water containing (TTHMs) trihalomethanes in excess of the MCL over many years may experience problems with their liver, kidneys, or central nervous system, and may have an increased risk of getting cancer.  

April - June 2022 
TTHM Running Annual Average (ppb)
TTHM MCL (ppb)
DBP1 - 133 North Common Road 8180
DBP2 - 86 East Road6980

What happened?   

Our water system purchases 100% of our drinking water from the City of Fitchburg who treats the water with filtration and adds chlorine disinfectant as part of the treatment process. Westminster does not add any additional disinfectants, such as chlorine, to the water. TTHMs are a byproduct of chlorine disinfection which forms when chlorine combines with natural organic matter commonly found in surface water supplies and sometimes in groundwater sources. TTHM levels can vary depending on a number of factors including the amount of chlorine used, amount of organic plant material in water sources, temperature, water age and seasons. TTHM levels must be controlled while also maintaining appropriate levels of disinfectant in the water necessary to avoid bacterial issues.  

What is being done? 

  • We are working closely with MassDEP, the City of Fitchburg and a consultant to investigate the cause of the elevated levels and determine appropriate corrective actions to be taken. We will be flushing affected areas as an interim measure. Some customers may experience water discoloration during the flushing events. 

What can you do to reduce exposure?  

Where to find more information? 

Frequently Asked Questions About Total Trihalomethanes (TTHM) 

PDF icon TTHM FAQs940.17 KB