Uranium more ‘problematic’ than arsenic in Wilton wells

The results of the Wilton Health Department’s voluntary well testing program are in, and they show that uranium levels in town are more “problematic” than arsenic levels, said Health Department Director Barry Bogle.
The department announced in February it would be working closely with the Connecticut Department of Public Health (DPH) to conduct the program, through which random wells in town were tested to evaluate the presence of the metals arsenic and uranium.
According to DPH epidemiologist Brian Toal, both arsenic and uranium are considered toxic and can have a variety of adverse health effects if people are exposed at high enough levels and for a long period of time.
Although the health department’s initial plan was to test 30 wells, it wound up testing a total of 80 due to “an overwhelming response” to its request for volunteers, said Bogle.
“We tried to accommodate as many as we could, given our limited resources,” he said. “It isn’t really a big sample size, but enough so to give us an indication of what’s going on.”


The Environmental Protection Agency (EPA)’s drinking water standard, or “action level,” for arsenic is 0.01 milligrams per liter (mg/l) or 10 parts per billion (ppb).
Although the results of the town’s well testing showed sporadic heightened levels of arsenic, said Bogle, “we don’t actually have much of a problem with arsenic at all.”
“Oftentimes what you’ll have is a variation in the reading because of the water levels,” he said. “It may be high at one point in time and maybe a lot lower at some other point in time. It’s not really a definitive number.”
Bogle said arsenic levels in Wilton wells are “pretty good.” Of the 80 wells tested, he said, arsenic was detected in seven samples.
“Two out of the 80 exceeded our action level of parts per billion, and there was just one outlier at 52 parts per billion, which is really high — a little bit over five times the action levels,” said Bogle.
“But that could be, like I said before, just a variation in the reading — the amount of arsenic that leached into the well water at that point in time.”
According to the DPH, “depending on local environmental conditions, arsenic can leach from soils or mineral deposits into groundwater,” but “the extent to which this occurs in Connecticut bedrock wells is uncertain.”
Arsenic has no smell or taste and is classified as a human cancer-causing agent. Arsenic has been associated with increased risk of lung, bladder and skin cancers.
Some people are more sensitive to arsenic than others. Symptoms associated with high levels of arsenic, according to the U.S. Environmental Protection Agency, include:

  • Numbness, tingling or pins and needles in the feet and hands with associated weakness.

  • Partial paralysis.

  • Stomach pain or diarrhea.

  • Patchy areas of darkened skin, redness and swelling.

  • Patchy areas or thickened outer skin layer.

  • Appearance of small “corns” or “warts” on the palms, soles of the feet or body.

The only way to know if a well is contaminated with arsenic is to test the water, according to the DPH, which recommends arsenic testing every five years.
Although the Wilton Health Department’s well testing “isn’t really a definitive test,” Bogle said, “it does give us an idea of where we may have some problems in terms of uranium, which seems to be the more problematic of the two.”


With regard to uranium, Bogle said, “we had a little bit more of a concern with the levels.”
“Thirty-three of the 80 wells had some level of uranium in them,” he said, “but we had 51.25% wells that tested negative for uranium.”
According to the EPA, the action level for uranium in drinking water is 30 ppb or 0.03 mg/l.
Although six of the 80 wells exceeded the uranium action level, Bogle said, 92.5% had uranium levels below the action level.
Because uranium is naturally present in bedrock in many places throughout Connecticut, according to the DPH, deep bedrock wells are susceptible to contamination and shallow wells are less susceptible.
However, the amount of uranium in bedrock and well water varies greatly from place to place, according to the DPH.
The type of uranium found in groundwater is not considered a radioactive risk and is therefore not a major cancer concern. However, the toxicity of the uranium metal has been associated with adverse effects on kidney function.
It is not possible to determine if water is safe to drink without testing, according to the DPH, which recommends testing wells for uranium every five years.


Bogle said well testing in Wilton is “an ongoing process,” and the health department is looking to create a database of test results.
“Over this coming summer, I’ll hopefully get an intern to build that database for us and we’ll have an idea of how many wells we have that are impacted by uranium and arsenic, or both,” he said.
Bogle said the database would grow as more homeowners in Wilton test their wells and provide the health department with their results.
“We have access to a database in the state department that provides information on all well completion reports,” he said. “However, because arsenic and uranium weren’t part of the standard portability test for private wells, that information isn’t there, so we’re actually relying on homeowners to do their own testing and provide us with that information.”
Bogle said the health department hopes to have “a better grasp on the amount of wells in town that are impacted by arsenic and uranium” before the year ends.
With the database, he said, “we’ll be better able to provide information to homeowners, potential buyers [and] Realtors as to what the water conditions are at the time of testing, and at the same time, advise homeowners to test more frequently.”

Remedies and resources

For wells that have unacceptable levels of arsenic, it can be removed with special filtration systems.
Carbon filters can be effective, and in some cases reverse osmosis systems will work, but each well and situation is different, so reverse osmosis does not work in all cases. The lab performing the tests should be able to advise if treatment is needed.
For those residents who were not selected for the department’s testing program and wish to have their well tested, a number of private laboratories can be contacted for testing. The cost for testing for both metals is reported to range between $65 and $100.
For more information, see the links below or call 860-509-7740 (DPH), or 203-563-0174: