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Siasconset Water Department

EPA monitoring tested this supplier for 60 contaminants and detected 5. A detection doesn't automatically mean the water is unsafe — the level and EPA source for each is below.

60
contaminants tested
5
detected
3,000
people served
8
health-based violations
Massachusetts rankingsLead in MassachusettsPFAS in Massachusetts
Water source
Ground water
Ownership
Local government
Counties served
Nantucket

Compliance record

Formal violations the EPA has on file for this supplier. A health-based violation means a contaminant limit or a required treatment was breached; the rest are monitoring or reporting failures — still violations, but not a measured health risk.

8
health-based violations
53
violations on file
1
still open
ViolationTypeStatusPeriod
MCL Health-based Resolved 2013-05-01 → 2013-05-31
MCL Health-based Resolved 2013-05-01 → 2013-05-31
MCL Health-based Resolved 2010-08-01 → 2010-08-31
MCL Health-based Resolved 2010-08-01 → 2010-08-31
MCL Health-based Resolved 2009-08-01 → 2009-08-31
MCL Health-based Resolved 2009-08-01 → 2009-08-31
MCL Health-based Resolved 2007-06-01 → 2007-06-30
MCL Health-based Resolved 2007-06-01 → 2007-06-30
Other Monitoring Unaddressed 2025-07-02
MR Monitoring Archived 2025-04-01 → 2025-06-30

Other contaminants detected

Each bar shows the measured level as a share of the EPA limit: green is well under, amber is close to it, red is over. For lead and copper the limit applies to exactly the 90th-percentile figure shown, so red there means a real exceedance. For everything else the limit applies to a running annual average while the figure is the 95th percentile of this system's samples — over 100% is worth reading, but is not by itself a violation. Where a single sample came in higher than that percentile, it is noted under the bar. Formal violations are listed separately.
ContaminantLevel vs EPA limitDetection rateSourcePeriod
Lead
0.0 mg/L 0%
of the EPA limit 0.0150 mg/L
 25/25 LCR 2025
Nitrate
1167 µg/L 12%
of the EPA limit 10000 µg/L
worst single sample: 1200 µg/L
24/28 SYR4 2012–2018
Barium
6.85 µg/L 0.3%
of the EPA limit 2000 µg/L
worst single sample: 7 µg/L
4/5 SYR4 2013–2019
Fluoride
188.5 µg/L 4.7%
of the EPA limit 4000 µg/L
worst single sample: 190 µg/L
4/5 SYR4 2013–2019
Arsenic
1 µg/L 10%
of the EPA limit 10 µg/L
 1/5 SYR4 2013–2019
55 contaminants tested, none detected
1,1,1-Trichloroethane1,1,2-Trichloroethane1,1-Dichloroethylene1,2,4-Trichlorobenzene1,2-DIBROMO-3-CHLOROPROPANE1,2-Dichloroethane1,2-Dichloropropane2,4,5-TP2,4-DAntimony, TotalAtrazineBhc-GammaBenzeneBenzo(A)PyreneBeryllium, TotalChlorobenzeneCyanideCadmiumCarbofuranCarbon TetrachlorideChlordaneChromiumDichloromethaneDalaponDi(2-ethylhexyl) AdipateDi(2-ethylhexyl) PhthalateDinosebEthylene DibromideEndrinEthylbenzeneHexachlorobenzeneHeptachlorHeptachlor EpoxideHexachlorocyclopentadieneLassoMercuryMethoxychlorNitriteOxamylPentachlorophenolPicloramSeleniumSimazineStyreneTetrachloroethyleneThallium, TotalTolueneToxapheneTrichloroethyleneVinyl ChlorideXylenes, Totalcis-1,2-DichloroethyleneO-DichlorobenzeneP-Dichlorobenzenetrans-1,2-Dichloroethylene

Utility contact

Contact
MARK J WILLETT
Phone
5082280022
Email
MWILLETT@NANTUCKET-MA.GOV

Frequently asked questions about Siasconset Water Department

Is Siasconset Water Department tap water safe to drink?

EPA monitoring detected 5 contaminants in Siasconset Water Department's water. A detection isn't the same as a violation — most levels are within federal limits. See each level and source above, and the utility's annual Consumer Confidence Report for its official compliance status.

What contaminants were detected in Siasconset Water Department's water?

EPA monitoring detected Lead, Nitrate, Barium, Fluoride, Arsenic. The full list with the level and data source for each is above.

How many people does Siasconset Water Department serve?

Siasconset Water Department reports serving 3,000 people in Massachusetts, per its EPA record.

Has Siasconset Water Department had any water quality violations?

The EPA has 53 violations on file for Siasconset Water Department, of which 8 are health-based (a contaminant limit or required treatment was breached) and 1 remain open. The rest are monitoring or reporting failures.

Where does this data come from?

Every figure is official EPA drinking-water monitoring — the Lead & Copper Rule, the UCMR-5 nationwide testing program, and the EPA Six-Year Review — not our own testing. Each number is labelled with its source and period.