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Update on Drinking Water 3-9-2018 (Revised)
Question and Answer Guide to TTHM’s Exceedance
Bellingham DPW Public Water System
  • March 2018  -
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.  Another official notice will be sent out shortly for the Quarter 1 of 2018.  

The correction of this issue is not a quick fix but good progress is being made.  The nature of the regulation will likely require that similar notices go out for the second and third quarters of 2018.

This document has been prepared from a MassDEP template by the Town to tell our customers what we are doing to resolve the situation and provide answers to common questions about TTHMs, drinking water standards, and operation of the public water system.  

Updated Information (See Table 1: TTHM Stage 2 Locational Running Annual Average (LRAA) Results & Compliance for more details)
  • Samples collected in February 2018 yielded result below 80 ppb.  This is a big improvement from levels of the prior two quarters that we over 100.
  • Due to the Running Annual Average (RAA) requirements of this regulation we will continue to be in a non-compliant state until the 3rd quarter 2018 sampling and possibly until the 4th quarter 2018 sampling, is completed.  The RAA metric is such that we need to kick out the high results we got in quarters three and four of 2017 to get an RAA below 80 ppb.
  • A public notice will be issued each quarter until we return to compliance.
  • Although the sample results from February 2018 are below 80 ppb, some were higher than the February 2017 results.  That has driven our RAA status Q1-2018 higher than the Q4-2017 status.  This gives the appearance that we are not making progress, but is a result of the RAA metric.
What is being done to get back to meeting the standard?

We continue to work closely with MassDEP and have brought in engineers from Wright Pierce to help us resolve this non-compliance issue.   

Since the initial non-compliance period (4th quarter 2017):
  • We have collected numerous additional water samples for analysis to gain a better knowledge base regarding the organics in our raw water and TTHM levels throughout our system and filtration processes.
  • We have purchased new lab equipment to enhance the in town sample analysis capabilities regarding organics.  This should allow us to be proactive when raw water quality changes occur to prevent future TTHM exceedance.  
  • Wright Pierce has undertaken a detailed filtration plant operations study
  • We have modified the chlorine output of the Hartford Ave plant – (Sample analysis and the recent TTHM results show this has had an immediate positive effect with February results below 80 ppb.)
  • Wright Pierce is currently drafting an action plan that we believe will eventually bring us back into compliance.  The action plan will include:  
  • Operators training on the complexities of balancing TTHM control with effective disinfection and other regulatory requirements.  
  • Minor changes to the physical equipment at the filtration plant and operation changes designed to remove the majority of the TTHM’s during the filter process.  Continued additional sampling and analysis:
  • Raw water sampling to monitor organics content,
  • Filtration plant process sampling to monitor filtration effectiveness,
  • Distribution System and Standpipe sampling to monitor TTHM levels in the 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









Q2 – 2017










Q3 – 2017










Q4 – 2017










Q1 – 2018










The underlined 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.

Sorry this following sections accidentially were cut off when posting on 3-9-2018.

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?’ (on right)
  • Click on ‘Water Filters/Water Treatment’
Contaminant Reduction Claims Guide
  • Click on ‘Volatile Organic Chemical (VOCs)’ (in table)
Below are several other web sites that could be 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 and HAA5s in drinking water and my health?

     If you have health questions about exposure to TTHMs or HAA5s 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) familiar with chemical exposures.~ 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.

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.