Westerly Water Department water quality: what the testing found

Westerly's water carries hexavalent chromium at 0.116 parts per billion. There is no federal drinking water standard for hexavalent chromium anywhere in the United States. Not a lenient one. None at all.

One government in the country has published a number. In July 2011, California's Office of Environmental Health Hazard Assessment set a public health goal of 0.02 ppb, the first in the nation for this substance, calculated as the concentration where lifetime cancer risk from drinking the water works out to one in a million.^[1]

Westerly reports 5.8 times that figure. And because no federal limit exists, the utility can report it, publish it, and be in the clear, which is exactly what has happened.

Rhode Island's shoreline town runs on wells rather than a reservoir, and that changes what shows up in the glass.

What's in Westerly tap water?

Westerly Water Department serves 35,298 people in one town, and it's the only groundwater system of the three we cover in Rhode Island.^[2] State-reported testing between 2015 and 2023 detected 27 substances, and 17 came in above published health guidelines.^[3]

Seventeen out of twenty-seven. That's a higher share than either of the surface-water systems up the road.

Every multiple in that right-hand column is measured against a health guideline from the Environmental Working Group, not against a legal limit.^[3:1] Those guidelines are built around long-term cancer risk. The legal limits sit in the middle column, and for nine of these seventeen the middle column says none.

Read the list by group and the shape of it comes clear. Seven of the seventeen are PFAS or hexavalent chromium, the two families nobody has finished regulating. Westerly's trihalomethane figure of 22.8 ppb is genuinely lower than Providence at 55.2 or Kent County at 49.9, and we're not going to pretend otherwise. This town's problem is a different one.

Where does hexavalent chromium come from?

Two places, and groundwater sees both.

Some of it occurs naturally, dissolving out of chromium-bearing rock and soil into the aquifer below. The rest is industrial. Chromium-6 has been used in plating, leather tanning, pigments, wood preservation and corrosion control for more than a century, and where it was handled it tends to end up in the water table underneath.

That's why this substance shows up on Westerly's report and barely registers on Providence's. Providence draws surface water from a protected reservoir and reads 0.00388 ppb, below the guideline. Westerly pumps from the ground, and the ground is where chromium sits.

Chlorine has nothing to do with it. Unlike the byproducts on this page, nothing at the treatment plant creates hexavalent chromium. It was already in the water when the water arrived.

What did the research on chromium-6 actually find?

California's 0.02 ppb goal wasn't invented. It sits on two bodies of evidence, and you should see both, including their limits.

The first is animal work. The National Toxicology Program ran two-year drinking water studies of hexavalent chromium in male and female rats and mice. It reported increased incidences of rare tumors of the squamous epithelium lining the oral cavity in rats, and of the epithelium lining the small intestine in mice, and concluded that the compound "was carcinogenic after administration in drinking water" to both species.^[4] The doses were nothing like tap water. Those studies went as high as 180 parts per million, more than a million times Westerly's 0.116 parts per billion, which is how rodent bioassays are run and is the honest way to describe them.

The second is human. California's own toxicologists reanalyzed cancer mortality data from villages in Liaoning Province, China, where wells near a ferrochromium plant had been heavily affected. Stomach cancer mortality in the affected villages ran 1.82 times the rate in the unaffected villages nearby (95% CI 1.11–2.91) and 1.69 times the rate for the whole province.^[5] A commentary published alongside it called the underlying data seriously limited, and also called this the highest chromium-6 water exposure a population large enough to study will ever have.^[6]

So what did California do with that? It didn't test anyone's kitchen tap. It took the animal and human findings, ran the standard cancer risk extrapolation down through the low-dose range, and asked one question: at what concentration in drinking water does lifetime cancer risk come to one in a million? The answer it published was 0.02 ppb.^[1:1]

That state-government figure is identical to the health guideline EWG uses, which means the benchmark Westerly is measured against isn't an advocacy number. It's a public health agency's arithmetic, and a second organization arrived at the same place.

The argument isn't settled, and we'll say so. EPA's IRIS program set an oral cancer slope factor for hexavalent chromium in 2024 based on the rat oral cavity tumors. A 2025 paper in Toxicological Sciences, written by authors at the consulting firm ToxStrategies, argues that those rat tumors are the wrong basis and reports finding no increased oral cancer risk in the human studies.^[7] Both sides of that dispute agree on one thing: EPA still has not set a drinking water limit for hexavalent chromium, and there is no date on which it will.

Which of these has no federal limit?

Nine of the seventeen, hexavalent chromium among them.^[8]

Sit with what that column means. For these nine, a utility could report any figure at all and still meet every federal drinking water standard in existence, because no standard was ever written. There's nothing to pass and nothing to fail, and nobody is required to fix a number that has no ceiling over it.

How much PFAS is in Westerly water?

Nine distinct PFAS compounds turned up in this system, and six of them read above health guidelines. That's more flagged PFAS than either of the other Rhode Island systems on this site.

The six above guideline are PFHxS at 169 times it, PFUnA at 45, PFNA at 41, PFDA at 38, PFOA at 33 and PFOS at 5.4.^[3:2] Three more were detected below their guidelines: PFHxA, PFBS and PFHpA.

Two federal-facing sources report different figures for this system and both are correct, so it's worth being precise about which is which. EWG publishes utility-level figures: PFOA at 2.93 ppt and PFOS at 1.63 ppt. Federal UCMR5 monitoring separately recorded highest single samples of 9.0 ng/L for PFOA, 7.0 for PFOS and 10.0 for PFBA. Parts per trillion and nanograms per liter are the same unit, so the gap isn't a conversion error. EWG averages across its data window, UCMR5 published peak individual samples, and legal compliance is judged on a running annual average, which is a third number again. A single sample above 4.0 ppt is not a violation of anything.

PFAS didn't come from the treatment plant either. These compounds were made for firefighting foam, stain repellents, grease-resistant packaging and non-stick coatings, they wash into groundwater, and they don't break down. The plant wasn't built to take them out.

Why is EPA's own health goal zero?

Because EPA could not identify any amount of PFOA or PFOS that carries no known risk.

When it finalized the PFAS rule in April 2024, it published two numbers for each of those compounds instead of one.^[9] The enforceable limit is 4.0 parts per trillion. The health goal is zero.

EPA defines that health goal as the level "below which there is no known or expected risk to health," margin of safety included.^[8:1] For these two it set that level at nothing at all, then set the enforceable limit at what it judged technically and economically achievable for water systems to hit. The 4.0 ppt figure is an engineering and cost judgment. EPA has never presented it as a safe dose.

Every PFOA and PFOS detection in Westerly's water sits above EPA's health goal, because any detection above zero does.

There's a date attached, too. EPA moved the compliance deadline for the PFAS limits from 2029 to April 2031.^[10] No utility in the country has to meet them for another five years. If the plan was to wait for the water department to handle this, five years is the length of the wait, and a baby born this year will be in kindergarten before it's over.

What does PFAS do inside a body?

ATSDR, the federal agency that studies environmental exposures, documents increased risk of kidney and testicular cancer, developmental effects in children including low birth weight and accelerated puberty, reduced immune response including diminished vaccine effectiveness, and increased cholesterol.^[11]

The C8 Science Panel studied a heavily exposed population in the mid-Ohio Valley and found a probable link between PFOA and high cholesterol, thyroid disease, kidney and testicular cancer, pregnancy-induced hypertension, and ulcerative colitis. A 2020 review by former panel members reported the cancer evidence as supportive but not definitive, consistent evidence on cholesterol, and good evidence for an effect on immune response. It also concluded that the overall epidemiologic evidence remains limited.^[12]

The immune findings are the ones parents tend to sit up for. A Faroese birth cohort measured PFAS and vaccine antibodies in 516 thirteen-year-olds. Diphtheria antibody concentrations fell about 25% for each doubling of PFOA in blood, and modeling of exposure at age 7 predicted losses of 10 to 30% in antibody levels six years later.^[13]

The Boston Birth Cohort found the same shape in an American population. Across 748 mother-child pairs, maternal PFHxS was significantly associated with lower measles antibody response in children after MMR vaccination, and PFHxS came out as a leading contributor when the whole PFAS mixture was analyzed together. The effect was more pronounced in Black children and in children born preterm.^[14] PFAS were detected in 90 to 100% of the mothers' blood.

PFHxS is the compound sitting at 169 times its health guideline in Westerly's water. Both of those studies measured PFAS in blood rather than in tap water, and both describe their evidence as suggestive. What they suggest is that a vaccine your child already received may be doing less than it should.

On pregnancy, a meta-analysis of 23 studies reported pooled odds ratios of 1.54 for preterm birth with PFOS, 1.52 for low birth weight with PFOS, and 1.40 for miscarriage with PFOA.^[15] The C8 reviewers are more cautious here and suggest reported birth weight reductions may reflect reverse causation or confounding, which is a real caveat and belongs on the page.

One more thing about this family of chemicals. Your body clears them slowly, so a level that never moves still adds to your total burden year after year. "Forever chemicals" describes the chemistry, not the marketing.

What about the byproducts and the nitrate?

Westerly's trihalomethanes read 22.8 ppb. That sits below the 41 µg/L where the January 2025 dose-response meta-analysis found bladder cancer risk turning statistically significant, and the federal ceiling of 80 ppb, written in 1998, is nowhere near it either.^[16][17] We're not going to build an argument on a number that doesn't support one.

The haloacetic acids are a different matter. HAA9 reads 14.4 ppb, which is 239 times its health guideline and the largest multiple on Westerly's whole list, and there is no federal limit for HAA9. A peer-reviewed analysis of US occurrence data concluded that haloacetic acids, brominated ones in particular, are more carcinogenic than trihalomethanes.^[18] The National Toxicology Program's 15th Report on Carcinogens lists selected haloacetic acids found as water disinfection byproducts.^[19] Trichloroacetic acid at 3.77 ppb and dichloroacetic acid at 2.47 ppb have no federal limit either.

Nitrate is where the age of the rules shows most plainly. The 10 ppm federal standard was recommended by the US Public Health Service in 1962 and written into law in 1974, and it was set to prevent methemoglobinemia, the acute infant condition known as blue baby syndrome.^[20] Cancer was never the endpoint it was designed around.

The National Cancer Institute published work in 2026 following 40,403 men for an average of 21.9 years. Men whose drinking water averaged above 10 mg/L of nitrate-nitrogen had elevated risk of total prostate cancer (HR 1.16) and aggressive prostate cancer (HR 1.22) compared to men at or below 1 mg/L.^[21] Westerly's 1.29 ppm sits far below that study's high group, and we're not claiming it doesn't. The point is what the 1962 limit was built for, and it wasn't built for this.

What happened with lead in 2024?

EPA collects a 90th-percentile lead result for every system, meaning nine out of ten sampled taps read at or below it. The action level is 0.015 mg/L. Westerly's filed results run like this.^[2:1]

The 2024 result came in above the action level, the highest figure in the run and the only exceedance in a record that goes back to 2012. It came back down in 2025.

Alongside it, EPA's compliance record lists an open Lead and Copper Rule violation for this system. It began 01/01/2025 and its status reads "Unaddressed."^[2:2] That's the state of the record as of the 2026 second-quarter extract, stated exactly as it's filed and with no interpretation added to it.

Here's what the 2024 spike does not tell you: anything about your house. Lead in tap water doesn't come from the wells. It comes out of your service line, your solder and your brass fittings, and it enters the water in the last few feet of the trip. A house on Beach Street with its original line and a house rebuilt in 2010 sit in the same 90th percentile and share nothing else.

Why does lead matter at any level at all?

Because the agencies have gone looking for a safe floor and haven't found one.

CDC's position is that no safe blood lead level in children has been identified, and that even low levels are associated with reduced IQ, reduced ability to pay attention, and lower academic achievement.^[22] EPA's health goal for lead is zero.^[8:2]

The evidence underneath that pooled seven long-term cohorts following 1,333 children from birth or infancy to ages 5 to 10. Blood lead rising from 2.4 to 10 µg/dL was associated with a 3.9-point IQ loss (95% CI 2.4–5.3), and the loss per unit of lead was steeper in the children whose maximum blood lead stayed below 7.5 µg/dL than in those above it.^[23] The damage is worst per microgram at the bottom of the range, which is the range ordinary American children live in.

Adults aren't outside it. A nationally representative cohort of 14,289 US adults followed for a median 19.3 years found blood lead rising from 1.0 to 6.7 µg/dL associated with all-cause mortality (HR 1.37), cardiovascular mortality (HR 1.70) and ischemic heart disease mortality (HR 2.08).^[24]

And drinking water is a current route, not a historical one. After Flint changed water sources without adequate corrosion control, the share of children under 5 with elevated blood lead rose from 2.4% to 4.9%, and 6.6 points in the neighborhoods with the highest water lead. The authors' conclusion was that water is a growing source of childhood lead exposure because of aging infrastructure.^[25]

Westerly's pipes are as old as Westerly.

Why doesn't the published number describe your tap?

Every figure on this page is a system figure. It's an average or a peak taken at fixed sampling points across a distribution network, on a schedule set by regulation, and then folded into one line for 35,298 people.

Groundwater makes the spread wider, not narrower. A system running on multiple wells isn't drawing the same water at every hour of every season, and chromium and nitrate readings can differ well to well. Disinfection byproducts keep forming while chlorinated water sits and travels, so a house at the end of a long run reads higher than the average. Lead is the most local of all, because it comes out of your own plumbing rather than out of the main in the street.

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

What can you do about it?

Start by finding out what's actually coming out of your faucet. We come to the house, test the water there, and tell you what came back whether or not it points toward buying anything. The test is free and nothing is attached to it. If your numbers don't call for a system, we'll say so and go.

Carbon filtration and reverse osmosis are the two filter classes generally used in homes against PFAS and disinfection byproducts, and EWG publishes its own guidance on choosing between them. Which one suits your house depends on what your water reads, because the groups on this page don't all behave the same way.

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

Book your free in-home water test and get a reading for your address instead of a reading for the town. Our Westerly page covers what else is worth knowing locally.

Water quality follows the utility, not the town line. Our Providence Water report and Kent County Water Authority report cover the other two systems in this part of Rhode Island.

Westerly Water Department FAQ

What's in Westerly Water Department tap water? State-reported testing between 2015 and 2023 detected 27 substances, and 17 came in above published health guidelines. The list is led by haloacetic acids (HAA9) at 14.4 ppb, PFHxS at 0.169 ppt, total trihalomethanes at 22.8 ppb and hexavalent chromium at 0.116 ppb. Nine distinct PFAS compounds were detected, six of them above guideline, and nine of the seventeen flagged substances have no federal limit at all.

Is there hexavalent chromium in Westerly water? Yes, at 0.116 ppb. There is no federal drinking water standard for hexavalent chromium anywhere in the United States. California's Office of Environmental Health Hazard Assessment published a public health goal of 0.02 ppb in 2011, set at the one-in-a-million lifetime cancer risk level and based on National Toxicology Program studies that found tumors in rats and mice given the compound in drinking water, plus a reanalysis of cancer mortality in Chinese villages with heavily affected wells. Westerly's level is 5.8 times that goal. The same 0.02 ppb figure is what EWG uses as its health guideline.

How much PFAS is in Westerly water? Nine distinct PFAS compounds were detected and six read above health guidelines: PFHxS, PFUnA, PFNA, PFDA, PFOA and PFOS. EWG reports PFOA at 2.93 ppt and PFOS at 1.63 ppt as utility-level figures, while federal UCMR5 monitoring recorded highest single samples of 9.0 ng/L for PFOA, 7.0 for PFOS and 10.0 for PFBA. EPA's own health goal for PFOA and PFOS is zero, defined as the level below which there is no known or expected risk, so the enforceable 4.0 ppt reflects what EPA judged feasible rather than what it considers safe. No utility has to comply until April 2031.

Did Westerly water exceed the lead action level? Yes. The 2024 90th-percentile result was 0.0167 mg/L against an action level of 0.015 mg/L, the only exceedance in a record running back to 2012. The 2025 result was 0.0051. EPA's compliance record also lists an open Lead and Copper Rule violation for this system that began 01/01/2025 with a status of "Unaddressed." Lead in tap water comes from service lines, solder and fixtures rather than from the wells, so a system-wide figure says nothing about any individual house.

Why does Westerly's water look different from Providence's? Because Westerly pumps groundwater and Providence treats surface water from a reservoir. Chlorination byproducts dominate a surface-water system, which is why Providence's trihalomethanes read 55.2 ppb against Westerly's 22.8. Groundwater instead picks up what's in the rock and what has soaked down into the aquifer, which is where hexavalent chromium and PFAS come from.

Which Westerly substances have no federal limit? Nine of the seventeen flagged: HAA9, trichloroacetic acid, dichloroacetic acid, chloroform, bromodichloromethane, dibromochloromethane, hexavalent chromium, PFUnA and PFDA. EPA has never set a Maximum Contaminant Level for any of them, so no legal threshold exists to measure them against. Against the only published health guidelines for those substances, HAA9 reads 239 times its guideline and hexavalent chromium 5.8 times its.

Substance levels and health-guideline multiples: EWG Tap Water Database profile for PWSID RI1559512, state-reported testing 2015–2023. Service population, lead 90th-percentile results and the Lead and Copper Rule violation record: EPA ECHO Safe Drinking Water Act extract, 2026Q2. PFAS peak samples: federal UCMR5 monitoring round. Pulled 2026-08-06.