Holliston Water Department water quality
Holliston, MA · serves 15,139 people (5,018 connections) · Groundwater · Local government · EPA ID MA2136000
Data: U.S. EPA · How we read the data · How we check it
Summary
PFAS above the 2024 federal limits. Systems have until 2029 to meet the PFAS limits.
Is it an emergency? No: PFAS limits are about years of exposure, not a glass of water, and nothing in EPA's data calls for you to stop drinking the water today. If your utility ever issues a boil-water or do-not-drink notice, follow it.
- PFAS
- Above limitPFOA, PFOS above the federal limit in EPA's 2023–2025 testing (PFOA 5.1 ppt vs a limit of 4 ppt, PFOS 5.9 ppt vs a limit of 4 ppt, where ppt = parts per trillion).
- Lead
- Below action level2.9 ppb (parts per billion) at the 90th percentile: 9 in 10 homes sampled were at or below it. Action level 15 ppb, falling to 10 ppb in Nov 2027. Monitoring period ending Dec 2025. Your home's pipes can make yours higher.
- Violations
- Resolved4 health-based violations since 2016, most recently Apr 2017.
- Pregnant, or mixing baby formula with tap water? Babies drink more water for their size, so PFAS exposure matters more for them. Consider bottled water or a filter certified for PFAS for formula, and ask your doctor. Health effects.
- To lower your PFAS exposure now, a home filter certified for PFAS reduction works (reverse osmosis, or activated carbon certified to NSF/ANSI 53 or 58). Filters for these results.
- Built before 1986, or not sure what your service line is made of? Check your service line and test your tap. Utility data can't show your pipes.
- Tested your own tap? Compare your result with these numbers. Moving? Compare this system with another.
- Read Holliston Water Department's annual water quality report (Consumer Confidence Report). It lists every regulated contaminant tested and is usually on the utility's website or mailed with your bill, and you can also request it at (508) 429-0603. EPA: how to find it.
PFAS (“forever chemicals”)
EPA UCMR 5: 4 entry points tested Apr 2025 to Sep 2025. "Average" is the highest entry-point average (non-detects counted as zero), the way EPA compares UCMR 5 results to the limits. ppt = parts per trillion. These results do not determine compliance.
| Contaminant | Highest average |
|---|---|
| PFOA Above limit Limit 4 ppt | 5.1 ppt 1.28× the limit |
| PFOS Above limit Limit 4 ppt | 5.9 ppt 1.47× the limit |
| PFHxS Not detected Limit 10 ppt | – |
| PFNA Not detected Limit 10 ppt | – |
| HFPO-DA (GenX) Not detected Limit 10 ppt | – |
| Hazard Index (a combined score for PFHxS, PFNA, GenX and PFBS, where above 1 is over the limit) Detected, below limit Limit 1 | 0.0019 |
| PFBS Detected, below limit Guideline 2,000 ppt | 3.7 ppt |
| PFBA Not detected Guideline 6,000 ppt | – |
| PFHxA Detected, below limit Guideline 3,000 ppt | 3.45 ppt |
| PFPeA Detected, no limit | 1.65 ppt |
For context: the PFOA average is higher than at 79% of the Massachusetts systems EPA tested and the PFOS average is higher than at 89% of the Massachusetts systems EPA tested.
29 PFAS tested, 5 detected at least once. "Not detected" means below EPA's reporting limit (about 2 to 20 ppt depending on the chemical), not proven zero. PFAS not listed were not detected. The limits for PFHxS, PFNA, GenX and the Hazard Index were proposed for rescission in May 2026. That proposal is not final. Systems have until 2029 to meet the limits.
Lithium
Not detected in 8 samples (reporting limit 9 ppb). About lithium.
Lead and copper
Latest 90th percentile: 2.9 ppb lead (Jan 2025 – Dec 2025). Below action level
| Monitoring period | Lead (90th pct.) |
|---|---|
| Jan 2025 – Dec 2025 | 2.9 ppb |
| Jan 2024 – Dec 2024 | 1.4 ppb |
| Jan 2023 – Jun 2023 | 0 ppb |
Earlier results (9)
| Jul 2022 – Dec 2022 | 0 ppb |
| Jan 2018 – Dec 2020 | 2.9 ppb |
| Jan 2015 – Dec 2017 | 2.6 ppb |
| Jan 2012 – Dec 2014 | 3 ppb |
| Jan 2011 – Dec 2011 | 3.6 ppb |
| Jul 2007 – Jun 2010 | 12 ppb |
| Jul 2004 – Jun 2007 | 4 ppb |
| Jul 2001 – Jun 2004 | 2 ppb |
| Jul 2000 – Jun 2001 | 3 ppb |
Copper 90th percentile: 2.66 ppm (Dec 1992), action level 1,300 ppb.
Lead comes from pipes and fixtures, not the source water, so it varies home to home. The 90th percentile means 9 in 10 sampled homes were at or below it. More on lead.
Violations
| When | What happened |
|---|---|
| Jan 2017 – Apr 2017 2 times | The running annual average for TTHM was above the legal limit. EPA record: TTHM · Maximum Contaminant Level Violation, Average (limit 0.080 mg/L) Resolved |
| Jan 2017 – Apr 2017 2 times | The running annual average for Total Haloacetic Acids (HAA5) was above the legal limit. EPA record: Total Haloacetic Acids (HAA5) · Maximum Contaminant Level Violation, Average (limit 0.060 mg/L) Resolved |
Health-based violations mean a contaminant exceeded a limit or a required treatment step was missed. Monitoring and reporting violations mean required tests or reports were late or missing, so the water's quality during that time is unknown. The total includes every violation in EPA's records, most of them paperwork.
Earlier EPA testing (2013–2020)
| Contaminant | Highest | Guideline |
|---|---|---|
| Vanadium | 0.3 ppb | 21 ppb |
| Strontium | 0.16 ppm | 1.5 ppm |
| Chlorate | 593 ppb | 210 ppb |
| Chromium-6 | 0.42 ppb | – |
| 1,4-Dioxane | 0.12 ppb | 0.35 ppb |
Where it serves
Holliston
ZIP codes the system reported serving: 01746
Nearby utilities
- Medway Water Department Medway · 3 mi · PFAS above limit
- Milford Water Department Milford · 5 mi · PFAS above limit
- Millis Water Dept Millis · 5 mi · PFAS above limit
- Hopkinton Water Department Hopkinton · 5 mi · PFAS above limit
- Hopedale Water Department Hopedale · 6 mi · PFAS above limit
- Medfield Water Dept. Medfield · 8 mi · PFAS above limit
Questions
Is Holliston Water Department water safe to drink?
Holliston Water Department had 4 health-based violations since 2016, all since resolved. EPA testing found PFAS above the 2024 federal limits, which systems must meet by 2029. Federal data can't tell you about your own pipes: lead comes from service lines and plumbing, so test your tap if your home was built before 1986. For the official word, read the utility's annual Consumer Confidence Report.
Does Holliston Water Department water have PFAS?
Yes. EPA's 2023–2025 testing of Holliston Water Department found 5 PFAS at least once. The highest entry-point averages were above the federal limit for PFOA and PFOS: PFOA 5.1 ppt, PFOS 5.9 ppt (limit 4 ppt for PFOA and PFOS, 10 ppt for the others).
What is the lead level in Holliston Water Department water?
The most recent 90th-percentile lead result for Holliston Water Department is 2.9 ppb, for the period ending Dec 2025. The federal action level is 15 ppb, falling to 10 ppb in November 2027. The 90th percentile means 9 in 10 homes sampled were at or below this number. Individual homes can be higher.
Check these numbers yourself
Every figure on this page comes from public EPA records. You don't have to take our word for it:
- EPA's own report for MA2136000: violations, enforcement and inspections, straight from EPA.
- EPA UCMR 5 data: the PFAS and lithium results (search the file for PWSID MA2136000).
- EPA SDWIS download: the lead results, population and violation records we use.
- The utility's annual water quality report (Consumer Confidence Report): ask Holliston Water Department at (508) 429-0603, or see EPA's guide to finding it.
Found something that doesn't match? Tell us and we'll check it against EPA's records. How we check our data.
Source: U.S. EPA drinking water records and PFAS testing (UCMR 5). How we read the data.