District Headquarters

50 Elm St, Dedham, MA 02026

During Office Hours:

781-329-7090

After Hours Emergency:

781-326-1250

Total Trihalomethanes (TTHM) Maximum Contamination Level Tier 2 Violation

UPDATE: The Dedham-Westwood Water District Has Achieved Tier 2 Compliance for Total Trihalomethanes

The Dedham – Westwood Water District is pleased to announce that we have achieved compliance and are no longer in violation of a Tier 2 Massachusetts Drinking Water Regulation. Together, our team of water professionals executed a plan to reduce the locational running annual average (LRAA) for total trihalomethanes (TTHM) in the public drinking water supply, including flushing the water distribution system, blending water from the Massachusetts Water Resources Authority (MWRA), and continually sampling and monitoring the levels of TTHM in the water to ensure our actions were having an impact and to protect public health and safety.

TTHM Compliance

Sample Location Q2 (Apr – Jun) Q3 (Jul – Sep) Q4 (Oct – Dec) Q1 (Jan – Mar) OEL Q1LRAA
Dedham Medical Associates Date: 4/6/2021
ppb 58
Date: 7/8/2021
ppb 89
Date: 10/7/2021
ppb 118
Date: 1/6/2022
ppb 24
6473
Getty Gas Station Date: 4/6/2021
ppb 33
Date: 7/8/2021
ppb 46
Date: 10/7/2021
ppb 81
Date: 1/6/2022
ppb 57
6054
East Dedham Fire Station Date: 4/6/2021
ppb 45
Date: 7/8/2021
ppb 64
Date: 10/7/2021
ppb 42
Date: 1/6/2022
ppb 24
3944
Far Reach Pump Station Date: 4/6/2021
ppb 58
Date: 7/8/2021
ppb 89
Date: 10/7/2021
ppb 109
Date: 1/6/2022
ppb 23
6170
MCL = 80 (ppb) Was OEL exceeded NOWas the MCL exceeded NO

TTHMs are a group of disinfection byproducts that form when chlorine compounds, which are used to disinfect water, react with other naturally occurring chemicals in the water. They are colorless and will evaporate out into the air. There are four significant TTHM (chloroform, bromoform, bromodichloromethane, and dibromochloromethane) potentially found in disinfected drinking water and their combined concentration is referred to as total TTHM. 

The Dedham-Westwood Water District is working with the MWRA to continue to blend the water supply, while our consultant, Weston & Sampson is in the process of designing an enhance treatment process to our Bridge Street Water Treatment Plant that includes the installation of tank mixers, aerators, and vents. We anticipate implementing the procurement process to begin in the spring of 2022, with construction to follow later in the year.  

We will continue to monitor the public drinking water supply for all regulated inorganic substances, synthetic organics, volatile organic compounds (vocs), Total Coliform, e.coli bacteria, unregulated (secondary) substances, organic disinfection byproducts, radionuclides, as well as lead and copper. Our team is committed to providing clean, safe water. As stewards of this valuable resource, we take our job to protect public health and safety seriously. Our team of 30+ professionals work around the clock to provide reliable, cost-effective, high-quality water service that protects public health, promotes environmental stewardship, maintains customer confidence, and supports economic development and sustainability.

We are here to answer your questions, call our water quality hotline to speak with a live representative Monday through Friday between the hours of 8 AM and 5 PM at (800) 279-8810 or email us at waterquality@dwwd.org

There will be a Board of Water Commissioners Special Business Meeting on Thursday June 30, 2022 at 6:30 PM.  This meeting will be virtual only. Please see the agenda page, which is posted when available, for more information including exemptions for executive session and joining instructions.
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