Westerly's tap water carries a chemical that no federal rule limits

Hexavalent chromium reads 0.116 parts per billion in Westerly's water, and there is no federal drinking water standard for it. Not in Rhode Island, not in any other state, nowhere in the United States.^[1][2]

EPA has never set a Maximum Contaminant Level for chromium-6 specifically. There's a limit for total chromium, which lumps it together with the harmless nutritional form, and that's all. For the form in question, a utility could report any figure at all and still meet every federal drinking water standard in existence, because none was written.

Westerly draws groundwater, the only system on this site that does. It serves about 35,298 people, and testing reported to the state between 2015 and 2023 found 27 substances, with 17 above published health guidelines.^[1:1] The chromium is the one with nothing behind it.

Is Westerly tap water safe to drink?

Westerly Water Department meets the federal limits that exist for the substances that have them. Three things sit outside that sentence, and this page is about all three: a carcinogen with no standard, nine PFAS compounds, and a lead reading from 2024.

Start with the chromium, because one government did set a number for it.

What number exists for chromium-6, and who set it?

California's Office of Environmental Health Hazard Assessment published a public health goal of 0.02 ppb in July 2011, the first in the country. It's set at the level estimated to carry a one-in-a-million lifetime cancer risk.^[3]

Westerly reads 0.116. That's 5.8 times a state health agency's cancer-risk goal. The same 0.02 figure is what the Environmental Working Group publishes as its health guideline. Those two numbers were arrived at separately. When the multiple on this page is measured against EWG's guideline, it's being measured against a benchmark a state government independently landed on.

The evidence underneath it starts with a two-year rodent bioassay. The National Toxicology Program gave sodium dichromate dihydrate in drinking water to rats and mice for two years and found squamous cell carcinoma of the oral mucosa in rats and adenoma and carcinoma of the small intestine in mice, with tumor incidence rising by dose.^[4]

Be clear about what that study did and didn't do. The doses ran from 14.3 to 516 mg/L of the compound, which is orders of magnitude above anything measured in a public water supply. It establishes that chromium-6 causes tumors when swallowed, in two species, in the gut and the mouth rather than the lung. Turning that into a drinking water number is the extrapolation OEHHA performed, and 0.02 ppb is what came out of it.

There's human data too, and it's thin by design, because populations drinking chromium-6 at high concentrations are rare. California researchers reanalyzed mortality in villages in Liaoning Province, China, near a ferrochromium plant. Stomach cancer mortality in the regions with chromium-6 in the groundwater was elevated against the neighboring unexposed regions (rate ratio 1.82, 95% CI 1.11 to 2.91) and against the province as a whole (1.69, 1.12 to 2.44).^[5] The authors call their own data limited. An accompanying commentary in the same journal describes serious limitations in the data and methods, along with a publication history that included a retracted paper, while noting this is probably the highest chromium-6 water exposure any population large enough to study will ever have.^[6] Those villages were drinking concentrations far above Westerly's.

What survives all that caution is this: chromium-6 causes cancer when it's swallowed, the only cancer-based number anyone has published is 0.02 ppb, and Westerly's water is at 0.116 with no rule requiring anything at all.

How much PFAS is in Westerly's water?

Nine distinct PFAS compounds were detected, and six of them read above health guidelines: PFHxS, PFUnA, PFNA, PFDA, PFOA and PFOS. PFBS, PFHpA and PFHxA were also detected, below theirs.^[1:2]

Federal UCMR5 monitoring recorded higher peak single samples in this system than EWG's utility-level figures: 9.0 ng/L for PFOA and 7.0 for PFOS.^[7] Both figures are correct and they measure different things. A part per trillion and a nanogram per liter are identical, so nothing was lost in conversion. EWG averages across its data window, UCMR5 reported the highest single sample it drew, and legal compliance is judged on a running annual average, which is a third number again.

Now the regulatory picture. When EPA finalized the PFAS rule in April 2024 it published two numbers for PFOA and PFOS: an enforceable limit of 4.0 ppt, and a health goal of zero.^[8] EPA defines a health goal as the level below which there's no known or expected risk to health, margin of safety included.^[2:1] It could not identify such a level for either compound, so it set the goal at nothing at all and set the enforceable figure at what it judged achievable for water systems. Every PFOA and PFOS detection in Westerly is above EPA's health goal, because any detection above zero is.

And the deadline moved from 2029 to April 2031.^[9] Five more years before any utility in the country has to meet those limits.

PFAS don't leave. Your body clears them slowly, so a level that never changes keeps adding to what you're carrying.

What does PFAS do to a child's immune system?

ATSDR documents increased risk of kidney and testicular cancer, developmental effects in children including low birth weight and accelerated puberty, raised cholesterol, and reduced immune response including diminished vaccine effectiveness.^[10]

That last one has been measured twice in ways that matter here. Researchers following a Faroese birth cohort tested 516 children at thirteen for both PFAS and vaccine antibodies. Diphtheria antibody concentrations fell about 25% for each doubling of PFOA in blood, and modeling of exposure at age 7 predicted antibody losses of 10% to 30% six years later.^[11] Few associations appeared for tetanus.

An American cohort points the same way. Across 748 mother-child pairs in Boston, maternal PFHxS was significantly associated with lower measles antibody response after MMR vaccination, and PFHxS was a leading contributor when the full PFAS mixture was analyzed together.^[12] The association was more pronounced in Black children and in children born preterm. No association appeared for rubella, and the authors describe the evidence as suggestive.

Both studies measured PFAS in blood or plasma rather than in drinking water. PFHxS is the compound sitting at 169 times its health guideline in Westerly's water, and what these studies suggest is that a vaccine your child already received may work less well.

What's on Westerly's lead record right now?

Two things, and they're current.

Westerly's 90th-percentile lead result was 0.0167 mg/L in 2024, above the federal action level of 0.015. It read 0.0051 in 2025.^[7:1] Going above the action level isn't a violation of a legal limit; it's a trigger that requires a utility to act and to notify customers.

Separately, the EPA compliance record lists a Lead and Copper Rule violation with a start date of 01/01/2025, status "Unaddressed."^[7:2] That's the record as of the 2026Q2 extract, stated as it appears, with no inference about why.

Lead itself doesn't come from the aquifer. It dissolves out of the service line into your house, out of solder in copper joints, and out of brass fittings, which is the stretch of pipe the homeowner owns. Congress banned lead solder and lead pipe in plumbing connected to public water systems in 1986, so anything plumbed before then may contain it.^[13]

The CDC has identified no safe blood lead level in children, and links even low levels to reduced IQ, reduced ability to pay attention and lower academic achievement.^[14] The pooled analysis behind that followed 1,333 children across seven birth cohorts and found IQ falling as blood lead rose, with the steepest losses per unit at the lowest exposures and measurable deficits in children whose peak reading stayed under 7.5 µg/dL.^[15] That work measured lead in blood rather than in water. EPA's health goal for lead is zero.^[2:2]

A 90th percentile means one in ten of the homes sampled read above the published figure. In 2024 the published figure itself was above the action level.

What about the chlorination byproducts?

They're on the list, and Westerly's profile here is different from the surface water systems in this state. Total trihalomethanes read 22.8 ppb, below the 41 µg/L level where a 2025 dose-response meta-analysis found bladder cancer risk statistically significant. We're not going to pretend otherwise.

The haloacetic acids are the ones worth your attention. HAA9 reads 14.4 ppb, and it has no federal limit, which puts it 239 times EWG's health guideline.^[1:3] Trichloroacetic acid at 3.77 ppb, dichloroacetic acid at 2.47, bromodichloromethane at 1.34, chloroform at 2.01 and dibromochloromethane at 0.769 have no federal limits either. Counting hexavalent chromium and PFDA and PFUnA, that's most of Westerly's flagged list sitting outside the rulebook entirely.

Toxicological assessment finds haloacetic acids, and brominated ones in particular, more carcinogenic than trihalomethanes, and the National Toxicology Program's 15th Report on Carcinogens lists selected haloacetic acids found as water disinfection byproducts.^[16][17] HAA5, the only one of the group with a federal ceiling, reads 7.40 ppb against a limit of 60.

Why doesn't the published number describe your tap?

Because every figure on this page is a system number. It's an average or a peak taken at fixed sampling points across the distribution network, on a schedule set by regulation, standing in for 35,298 people.^[1:4][7:3]

Your house has its own service line, its own plumbing age, its own hours when water sits still in the pipe, and its own distance from where the water is pumped and treated. Lead is decided inside your own walls, which is exactly why a 2024 system-wide reading above the action level tells you the direction of the problem and nothing about your kitchen.

The published number describes a town. Only a test at your sink describes your family.

What can you do about it?

Get a reading for your address. We come to the house, sample the water at your tap, and tell you what came back whether or not it points toward buying anything. Nothing is charged for the visit and nothing is expected after it. Plenty of houses turn out not to warrant a system, and we say so on the spot.

Carbon filtration and reverse osmosis are the two filter classes generally used in homes against PFAS, dissolved metals and disinfection byproducts, and which one fits depends on what your water actually reads. Westerly's list is unusual enough that guessing from a town-level average would be a poor way to choose.

Our systems run $3,995, $5,495 and $6,995, with financing available and every price published before anyone knocks on your door. A licensed plumber does the install, you own the equipment outright with no rental and no monthly fee, and there's a 156-day money-back guarantee on it.

Book your free in-home water test and find out what's in your water rather than what's in the town's average.

Full detail on the system is in the department's full testing record. For contrast, the Providence lead series shows what happens after an exceedance gets worked on, Cranston, split between two utilities, gets two different answers by address, and Coventry, where part of town is on wells, has a different question to settle first.

Westerly questions we get asked

Is Westerly tap water safe to drink? Westerly Water Department meets the federal limits that exist for the substances that have them. Testing reported to the state between 2015 and 2023 found 27 substances and 17 above published health guidelines, and seven of those carry no federal limit at all, including hexavalent chromium at 0.116 ppb. Nine PFAS compounds were detected, six above guideline. The 2024 lead 90th-percentile result of 0.0167 mg/L was above the federal action level of 0.015, and a Lead and Copper Rule violation with a start date of 01/01/2025 is recorded as Unaddressed.

What is hexavalent chromium and why is there no limit? It's the industrial form of chromium, and EPA has never set a drinking water standard for it anywhere in the United States. The federal limit covers total chromium, which combines it with the harmless nutritional form. The only cancer-based benchmark published for it is California OEHHA's public health goal of 0.02 ppb, set at a one-in-a-million lifetime cancer risk. Westerly reads 0.116 ppb, which is 5.8 times that goal, and EWG's health guideline is the same 0.02 figure.

What is the evidence that chromium-6 in water causes cancer? A two-year National Toxicology Program bioassay gave chromium-6 in drinking water to rats and mice and found squamous cell carcinoma of the oral mucosa in rats and small intestine tumors in mice, at doses far above environmental levels. Human evidence comes mainly from villages in Liaoning Province, China, where stomach cancer mortality was elevated against unexposed neighboring regions (rate ratio 1.82, 95% CI 1.11 to 2.91), in a study whose authors and reviewers both describe the data as limited. California's 0.02 ppb goal is an extrapolation from that body of work.

Is there PFAS in Westerly's water? Nine distinct PFAS compounds were detected and six read above health guidelines: PFHxS at 169 times its guideline, PFUnA at 45, PFNA at 41, PFDA at 38, PFOA at 33 and PFOS at 5.4. PFOA reads 2.93 ppt on EWG's utility figure against a federal limit of 4.0, while federal UCMR5 monitoring recorded a peak single sample of 9.0 ng/L, the same unit. EPA's health goal for PFOA and PFOS is zero, and compliance with the 4.0 ppt limits isn't required until April 2031.

Does Westerly have a lead problem? The 2024 90th-percentile lead result was 0.0167 mg/L, above the 0.015 action level, and 2025 read 0.0051. Crossing that level triggers treatment changes and customer notification rather than breaking a legal limit. The compliance record also lists a Lead and Copper Rule violation with a start date of 01/01/2025, status Unaddressed. Lead comes from service lines, solder and brass fittings inside your own property, so the town figure can't describe a specific house, and CDC has identified no safe blood lead level in children.

Substance levels and health-guideline multiples: EWG Tap Water Database profile for PWSID RI1559512, state-reported testing 2015 to 2023. Lead 90th-percentile results, PFAS peak samples and the Lead and Copper Rule violation record: EPA ECHO Safe Drinking Water Act extract, 2026Q2. Pulled 2026-08-06.