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To all customers of the Bellingham DPW Water and Sewer Division located in Bellingham, Massachusetts
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 Trihalomenthanes (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 four specific locations in the distribution system.  The results of this quarter’s sampling, which were received on November 16, 2017, show that our system exceeds the standard or maximum contaminant level (MCL) for TTHMs at three out of four locations.  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):

TTHM Running Annual Average (ppb)
DBP1 – 79 Hartford Ave.
DBP2 – 20 Cranberry Meadow
DBP4 – 342 Hartford Ave.
DBP5 – 115 North Main St.

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.  

What happened?  What is being done?
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, and seasons.  We must control TTHM levels while also maintaining appropriate levels of disinfectant in the water necessary to avoid bacterial issues.  Our water system is working with MassDEP on evaluating operations with the intention of correcting this issue.

For more information please visit our website at or contact Don DiMartino, DPW Director, at 508-966-5816.

Please share this information with all the other people who drink this water, especially those who may not have received this notice directly (for example, people in apartments, nursing homes, schools, and businesses). You can do this by posting this notice in a public place or distributing copies by hand or mail.
This notice is being sent to you by Bellingham DPW             PWS ID#: 2025000         Date distributed: 12/5/2017

Mass Department of Environmental Protection has prepared this very informative Question and Answer Guide to TTHM’s Exceedance of Bellingham DPW Public Water System in November of 2017.

At the end of this Q&A document, the DPW has added information that is an update of history and current activities underway to resolve the TTHM Exceedance.

Customers of the Town of Bellingham DPW Water and Sewer Division were previously notified that their drinking water exceeded the standard for Total Trihalomethanes (TTHMs) based on analysis of quarterly routine water samples collected by the Town during Quarter 4 of 2017.  This document has been prepared for the Town to assist its customers with some common questions about TTHMs, drinking water standards, and operation of the public water system.  

Why did the Town provide the public notice?

All public water systems are required by state and federal law to notify users of any exceedence of any water quality standard and any other noncompliance events affecting their water system.  The purpose of the public notice is to keep consumers informed about water quality.  Public notification is required to be repeated every three months until the public water system is in compliance with the standard.

What are TTHMs?

TTHMs are a group of chemicals known as disinfection byproducts.  They form when chlorine used for disinfection reacts with naturally occurring organic material that is found in source water and sometimes in groundwater.  They are colorless, and will evaporate out of the water into the air.  

Levels of TTHMs generally increase in the summer months due to the warmer temperatures, but can also be affected by seasonal changes in source water quality or by changing amounts of disinfection chemicals that are added to the water.  Water systems often can experience temporary increases in TTHMs due to short-term increases in chlorine disinfection.  Chlorine disinfection increases can occur when there is a water main break, when water systems are under repair, or when there is a potential microbial (example:  bacteria) problem or threat.

All water systems that use chlorine to disinfect the water are required by federal and state law to sample for TTHMs on a quarterly basis (once every three months) in several locations in the water distribution system.  

Why is chlorine added to the water?

Disinfectants are an essential element of drinking water treatment because of the barrier they provide against waterborne disease-causing microorganisms.  The practice of disinfection has nearly eliminated most acute waterborne diseases such as dysentery, typhoid fever, and cholera in the United States, though they are still common in some other countries.  These microbial diseases would otherwise be a major concern for children and other subgroups such as the elderly, immune compromised individuals, and pregnant women because of their greater vulnerabilities.

Chlorine (sodium hypochlorite) is commonly used in treatment operations and to treat the water as it travels through the pipes in the distribution system to prevent growth of microorganisms, or contamination from an outside source, such as during a water main break.  The Town adds chlorine to its drinking water system to maintain effective treatment for the removal of naturally occurring iron and manganese and to minimize the potential of microbial growth in the distribution system.

Where does the Town’s drinking water come from?

The Town obtains its water from fourteen groundwater sources, which are all treated at two treatment plants. The treatment facilities filter the water for the removal of iron and manganese. The water is disinfected with chlorine and sodium hydroxide is added to control corrosion from household plumbing.

Where does the Town monitor for TTHMs?

There are four locations that the Town samples each quarter for TTHM’s: 79 Hartford Avenue, 20 Cranberry Meadow Road, 342 Hartford Avenue, and 115 North Main Street, which represent compliance for the entire Town.    The sampling locations and the number of samples collected in each service area have been reviewed and approved by MassDEP.  

What is an MCL and how is compliance with the MCL determined?

Drinking water standards are set to protect against potential negative health effects from drinking water containing the chemicals.  The Maximum Contaminant Level (MCL) in drinking water is set so that the amount consumed does not exceed safe levels. Some MCLs address the daily amount consumed (for chemicals that pose an immediate risk), and others address the amount averaged over a long period of time (for chemicals that pose a long-term risk).  The TTHM MCL is set at a level to balance the immediate risk of bacterial contamination and the long-term risk of health effects such as cancer.  The United States Environmental Protection Agency and MassDEP have set an MCL for TTHMs of 80 parts per billion (ppb) or micrograms per liter (ug/L).  

Federal and state regulations require the Town to sample the four monitoring locations cited above every three months, including the month of warmest water temperature. The average of each sample location is then calculated each quarter over the last 12-month period, and these individual site averages (Locational Running Annual Average, or LRAA) are compared to the standard to determine whether the system is in compliance.  As of Quarter 4, 2017 (October - December), the highest Locational Running Annual Average (LRAA) for TTHMs was reported at 90 ppb at the 342 Hartford Avenue sampling location.

What is the TTHM sampling and compliance history of the Town?


            Table 1: TTHM Stage 2 Locational Running Annual Average (LRAA) Results & Compliance

Sample Date

Sample Locations

DBP1= 79 Hartford Ave.    DBP2= 20 Cranberry Meadow

DBP4= 342 Hartford Ave.    DBP5= 115 N. Main St.


Quarterly Results (ug/L)

4-Quarter Compliance (LRAA) Per Site









Q1 – 2017










Q2 – 2017










Q3 – 2017










Q4 – 2017










The highlighted results indicate a result above the TTHM standard of 80 ug/L.  Compliance with the LRAA MCL
for each location is determined by the numbers in the last four columns of the table, which represent an average
of all samples for each location collected in the Town’s water system over a 12-month compliance period.  

What are the health risks of TTHMs?  

The information provided below is based on available health studies.  Studies of populations that have been exposed to TTHMs suggest a possible connection between long-term TTHM exposure and certain types of cancer (e.g., bladder, colon, and rectal) and developmental (e.g. fetal growth) and reproductive effects (e.g. miscarriages, stillbirths).  In general, young children may be more susceptible to the effects from any chemical exposures, such as TTHMs, because their ability to metabolize chemicals is not mature and because their exposures may be greater for their size than in adults.  More research is being conducted to better understand the potential risks between TTHM exposures and these diseases. It is important that people be aware of these potential health effects from TTHM exposure.

Cancer risks generally accrue over lifetimes and very long periods of exposure.  Cancer risks are normally expressed as lifetime risks as a result of averaging daily exposure levels (associated with the lifetime daily average of ingesting 2 liters of drinking water/day) over a lifetime of 70 years. Based on these studies, and the potential for developmental and reproductive effects from TTHM exposure, women of childbearing age and pregnant women are the group that may be more susceptible to effects from TTHM exposure; however, children are always of concern with chemical exposures as noted above.  To reduce this risk, this group may wish to act with caution and reduce their exposures by following the recommendations in the next section.

What can customers do in the interim to reduce exposure to TTHMs?

If you are concerned about TTHMs and want to reduce your exposure, you can do the following:

  • Use bottled water or
  • Install point-of-use home water treatment systems on delivery lines in the house (faucet mount, pour-through pitcher style, and plumbed-in units);
Any filter that is purchased should be certified by National Sanitation Foundation (NSF), Underwriters Laboratories (UL) or the Water Quality Association (WQA) to remove TTHMs (look for the seals on the box).  The filters could be a pitcher style or a point-of-use treatment filter that can be mounted to the faucet, under the sink, or on the counter top.  These treatment devices are widely available for purchase at kitchen and bath stores or hardware stores.  A final option could be a whole house filter. This type of installation would likely require the services of a plumber which would increase the cost.  It is important that filters be used and the filters are changed according to manufacturer’s instructions.

For information on selecting a water treatment system that is right for you, visit NSF International at or call their hotline at 1-800-673-8010.  

Follow these links below to access water filtration systems certified by NSF to treat for TTHMs:
(Note: products certified for VOC reduction will reduce trihalomethanes)

  • Click on ‘Consumer Resources’ (on top)
  • Click on ‘What is NSF Certification?’
  • Click on ‘Water Filters/Water Treatment’
  • Click on ‘Contaminant Reduction Claims Guide’
  • Click on ‘Volatile Organic Chemical (VOCs)’ (in table)
Below are several other web sites that maybe helpful.

You can also contact the US EPA Safe Drinking Water Hotline at 1-800-426-4791. For more information on filters please refer to US EPA Filtration Facts at: EPA Water Health – Filtration Facts:

Who can I contact if I have additional questions or concerns about exposure to TTHMs in drinking water and my health?

     If you have health questions about exposure to TTHMs in drinking water you can contact the Environmental Toxicology Program at the Massachusetts Department of Public Health (617-624-5757).~
      If you are experiencing any symptoms or have medical care questions, you should consult with your health care provider and/or a specialist at an occupational and environmental medicine clinic (AOEC).~ You may visit to search for an AOEC clinic in your area, or call Toll Free: (888) 347-AOEC (2632).~ You may also contact a Pediatric specialist at Boston Children’s Hospital by calling the New England Pediatric Environmental Health Specialty Unit at 1-888-244-5314.

What steps are being taken to correct the situation?

TTHMs levels can vary depending on a number of factors including the amount of chlorine used, amount of organic material in water sources, temperature, water use, water storage, and season of the year.  Control of TTHM levels must be maintained while also applying appropriate levels of disinfectant in the water necessary to treat the water for contaminants and avoid bacterial issues.  

The Town is working with MassDEP on evaluating operations, water quality and treatment plant performance with the intention of developing a corrective action plan to correct this issue.

Public notification is required to be repeated every three months until the public water system is in compliance with the TTHM standard.

Who should customers contact for more information about the Public Water System?

The Town remains the primary contact for all questions regarding the Public Water System.  Any questions concerning sample results, status of projects, public notice inquires, etc. should be directed to Don DiMartino, DPW Director, at 508-966-5816.  

Recent History and actions taken to date:

A disinfection byproduct rule violation is completely new to the Bellingham DPW.  We have been preforming routine quarterly testing for disinfection byproducts since 2011.  We have experience slightly elevated results on a few occasions, but never at levels that triggered concern of a violation, until this summer.  

As we are very inexperienced at addressing this problem, we will be leaning heavily on MassDEP and the professional engineers at Wright Pierce, our water treatment consultants, to help us resolve this matter.  Our action plan has yet to be drafted, but we have a meeting scheduled for December 10th with MassDEP and Wright Pierce to start planning our approach.  

We experienced elevated TTHM numbers during our routine sample collection in August 2017.  It is not unusual to have elevated numbers in August due to higher water temperatures, but these were higher than typical summer readings.  The elevated readings did not trigger a violation; therefore, no notices were sent.  However, we were required to complete an Operation Evaluation Report (OER).  

We were surprised to see elevated results again in November.  In the past only the summer time sample showed elevated results.  This is an indication that there may be some changes in the organic material in our raw water.

Two things became clear when compiling the OER.  First, our sample collection locations and procedures needed to be improved.  Second, we have very little data to help determine what if anything has changed in our raw water quality.

To resolve the first item we have started to install sampling stations which will allow us to collect samples that are a better indication of the water in our distribution system.  All disinfection byproduct sampling locations that yielded high readings had very long service lines.  These customer’s taps are difficult to access and likely to yield samples that are not representative of the water in the distribution system.   DPW sampling staff has also been briefed on the detail sampling procedure.

DPW has expanded our sample collection and monitoring beyond basic requirements to hopefully build a usable database to analyze the cause of this issue.  DPW staff has begun to perform some raw water sampling and we have collected samples for analysis by state certified lab that we hope will give us a better indication of the organic material in our raw water.  As noted above, elevated levels of organic material when combined with chlorination can cause elevated TTHM numbers.

Some general discussion with our engineers after the elevated August results suggested we look into the age of water in our distribution system.  Age of the water in the system can cause elevated disinfectant byproduct results.  We have contracted with an engineering firm to run a water system hydraulic model analysis that will give us an indication as to where water is not cycling through the water system.  The water age model should be completed before the end of December.  The study should help us understand what is needed to keep water in the distribution system fresh and properly disinfected.  

The Hartford Ave plant was constructed with capabilities to address elevated organic material in our raw water; therefore, we should have options within the treatment plants capabilities of the plant to address this issue.   We cannot stop chlorination of the water system; that would risk bacterial contamination.   We can and do plan to make any modifications to the treatment process and distribution system necessary to get us back to compliance.  

When will we be back in compliance?

It could take several quarters of better sample results to bring our Locational Running Annual Average (LRAA) down below the maximum contamination limit. Under the disinfection byproduct rule only quarterly results are used in calculating the LRAA.  Therefore, it is likely that we will continue to exceed the limit when the February result comes, even if they are way down.  That will trigger the requirement to mail another notice.   It may take several quarters of lower results to get our LRAA back down to desired levels.  

Why three out of the four DEP approved sampling locations are in the northern part of the Town?

During treatment plant pilot testing the only wells that showed signs of possible problem levels of organic material were feeding raw water to the Hartford Ave plant.  None of the wells that are treated at the Wrentham Road plant showed any indication of organic material that would contribute to disinfection byproduct generation.

Why did I get a notice?  I am on a private well.

The logistics associated with mailing a notice are such that we can inexpensively send a notice to every address in Bellingham.  Mailing to all is significantly less costly than mailing to water customers only.  In addition, about 95% of the addresses in Bellingham are on the Town water system.