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Water Testing Results
Water Testing Results |
The Wellesley Water Division has confirmed elevated levels of PFAS6 in the drinking water during the period of April 2021 to July 2021. The exceedance was from our Morses Pond water treatment plant which has been testing at Non-Detect levels since July 2022. Water for all Wellesley residents and businesses is currently being supplied by the Town’s two other water treatment plants and the Massachusetts Water Resources Authority (MWRA). Below are testing results and additional information about our water supply to help you make informed decisions about your drinking water while we continue to monitor the water supply.
Water Testing Results
Sample Location by Entry Point to Distribution System | Monitoring Period | Sample Collection Date | PFAS6 Result (ng/L) | Avg (ng/L) | MCL (ng/L) |
Wellesley Avenue War Treatment Plant | Q1 Initial Q1 Confirmation Q1 Monthly Q2 Monthly Q2 Monthly Q2 Monthly Q3 Monthly Q3 Monthly Q3 Monthly Q4 Monthly Q4 Monthly Q4 Monthly Q5 Monthly Q5 Monthly Q5 Monthly Q6 Monthly Q6 Monthly Q6 Monthly Q7 Monthly Q7 Monthly Q7 Monthly Q8 Monthly Q8 Monthly Q8 Monthly Q9 Monthly Q9 Monthly Q9 Monthly Q10 Monthly | 4/21/21 5/3/21 6/16/21 7/29/21 8/31/21 9/17/21 10/22/21 11/15/21 Dec 1/12/22 2/23/22 3/16/22 4/14/22 5/10/22 6/30/22 7/22/22 8/19/22 9/30/22 10/27/22 11/29/22 12/15/22 1/24/23 2/9/23 3/22/23 5/2/23 5/19/23 6/15/23 7/12/23 | 10.4 12.9 8.3 9.5 8.4 11.7 11.1 13.1 N/A 11.6 11.0 10.8 9.1 9.8 7.3 10.7 12.2 14.8 15.2 17.8 13.5 9.9 12.4 12.9 8.4 9.6 9.4 9.3 | Q1: 10.5 Q2: 9.9 Q3: 12.1 Q4: 11.1 Q5: 9.2 Q6: 12.6 Q7: 15.5 Q8: 11.7 Q9: 9.1 | 20 |
Rosemary/Longfellow Water Treatment Plant | Q1 Initial Q1 Confirmation Q1 Monthly Q2 Monthly Q2 Monthly Q2 Monthly Q3 Monthly Q3 Monthly Q3 Monthly Q4 Monthly Q4 Monthly Q4 Monthly Q5 Monthly Q5 Monthly Q5 Monthly Q6 Monthly Q6 Monthly Q6 Monthly Q7 Monthly Q7 Monthly Q7 Monthly Q8 Monthly Q8 Monthly Q8 Monthly Q9 Monthly Q9 Monthly Q9 Monthly Q10 Monthly | /21/21 5/3/21 6/16/21 7/29/21 8/31/21 9/20/21 10/22/21 11/15/21 Dec 1/12/22 2/23/22 3/11/22 4/14/22 5/10/22 6/30/22 7/22/22 8/19/22 9/30/22 10/27/22 11/29/22 12/15/22 1/24/23 2/9/23 3/22/23 5/2/23 5/19/23 6/15/23 7/12/23 | 10.9 14.5 11.1 12.8 11.8 15.3 16.4 18.2 N/A 19.7 15.8 13.0 13.2 11.4 11.3 12.9 20.3 23.4 22.5 23.2 15.2 12.6 11.6 11.5 11.3 12.6 13.0 12.7 | Q1: 12.2 Q2: 13.3 Q3: 16.2 Q4: 16.1 Q5: 11.9 Q6: 18.9 Q7: 20.3 Q8: 12.0 Q9: 12.3 | 20 |
Morses Pond Water Treatment Plant | Q1 Initial Q1 Confirmation Q1 Monthly Q2 Monthly Q2 Monthly Q2 Monthly Q3 Monthly Q3 Monthly Q3 Monthly Q4 Monthly Q4 Monthly Q4 Monthly Q5 Monthly Q5 Monthly Q5 Monthly Q6 Monthly Q6 Monthly Q6 Monthly Q7 Monthly Q7 Monthly Q7 Monthly Q8 Monthly Q8 Monthly Q8 Monthly Q9 Monthly Q9 Monthly Q9 Monthly Q10 Monthly | 4/21/21 5/3/21 Off-line Off-line Off-line Off-line Off-line Off-line Off-line Off-line Off-line Off-line Off-line Off-line Off-line July August September October November December January February March April May June July | 45.1 52.6 Not Required Not Required Not Required Not Required Not Required Not Required Not Required Not Required Not Required Not Required Not Required Not Required Not Required Non-Detect Non-Detect Non-Detect Non-Detect Non-Detect Non-Detect Non-Detect Non-Detect Non-Detect Non-Detect Non-Detect Non-Detect Non-Detect | Q1: 32.6* OFF-LINE Q6: Non-Detect Q7: Non-Detect Q8: Non-Detect Q9: Non-Detect |
20 |
Purchased Water by Entry Point to Distribution System | Monitoring Period | Sample Collection Date | PFAS6 Result (ng/L) | Avg (ng/L)* | MCL (ng/L) |
Hegarty Pumping Station (Massachusetts Water Resources Authority - MWRA)** | Routine Routine Routine | January 2021 April 2021 May 2023 | 0 0 0 | 0 0 0 | 20 |
*Quarterly Average calculation per MADEP requirements.
**MWRA conducts sampling as required for their water supply, Wellesley is not responsible for sampling this water source.
Note: The location where elevated levels PFAS6 were reported (Morses Pond) is one of 4 active entrance points (or sources) that supply drinking water to our system. PFAS6 levels were reported below the 20 ng/L MCL at these other locations.
MCL = Maximum Contaminant Level
ng/L = nanograms per liter, equal to parts per trillion (ppt)
The location where elevated levels of PFAS6 was reported is the Morses Pond Wellfield, one of the three entrance points (POE) that supplies drinking water to our system. PFAS6 levels were reported below the 20 ng/L MCL at the other two POE locations.
Mass DEP Notice of Noncompliance
- Mass DEP PFAS Notice of Noncompliance can be found here if applicable (not applicable as of 5/4/2021).
Where Does My Drinking Water Come From? |
Wellesley’s local water supplies consist of ten wells located within the Town. Four wells tap into the Waban Brook alluvial aquifer and six wells tap into the Rosemary Brook alluvial aquifer. The water pumped from the ten wells is treated at our three corrosion control and iron/manganese removal facilities.
Wellesley operates three water treatment facilities. The primary purpose of these facilities is to provide the regulatory approved treatment technique (TT) for corrosion control under the Safe Drinking Water Act’s Lead and Copper Rule. These facilities provide the same treatment processes to all of our wells. The well water is oxidized and its pH is adjusted prior to filtration. The filter process removes the naturally occurring iron and manganese minerals in the raw water. The filtration units consist of anthracite, green sand and garnet sand. After filtration, the water cascades through a tray aerator, which removes naturally occurring carbon dioxide from the water. This aeration process removes the acidity from the water. The water is fluoridated and finally the water is disinfected with hypochlorite and detained in large holding tanks prior to being pumped into the distribution system.
Does my home get water from a particular supply well? No. We cannot say with any certainty that a particular household received water from a particular well, regardless of proximity of the well. Because water in our distribution system is a blend of water from our wells and the MWRA. This causes levels of PFAS to fluctuate throughout the water distribution system, it cannot be said for certain from where a particular address receives its water. As a matter of public health and regulatory requirements, the Town's outreach and response is based upon the results of all samples taken at our water supply well fields.