Roderick is the environmental health officer for Webster County in north-central Iowa, where a few thousand rural residents live among sprawling corn and soybean fields. Many draw their water from private wells, which are exempt from most federal testing and purity regulations. Roderick spreads the word that they aren’t exempt from danger.

More than 43 million Americans rely on private wells, which are subject to a patchwork of state and local regulations, including standards for new construction. But in most cases, residents are free to use outdated wells without having them tested or inspected. The practice is common despite concern about runoff from farms and industrial sites, plus cancer-causing minerals that can taint groundwater.

“You’re cooking with it. You’re cleaning with it. You’re bathing in it — and, nowadays, there are so many things that can make you sick,” Roderick said.

Federal experts estimate more than a fifth of private wells have concentrations of contaminants above levels considered safe.

Like many states, Iowa offers aid to homeowners who use well water. The state provides about $50,000 a year to each of its 99 counties to cover testing and help finance well repairs or treatment. The money comes from fees paid on agricultural chemical purchases, but about half goes unused every year, according to the Iowa Department of Natural Resources.

Roderick, who started her job in 2022, aims to spend every penny allotted to her county. Last spring, she snared an extra $40,000 that other counties hadn’t used. She promotes the program online and by mailing piles of postcards. Traveling the countryside in a hand-me-down SUV from the sheriff’s department, she collects water samples from outdoor spigots and sends them to a lab.

When she finds contamination, she can offer up to $1,000 of state grant money to help with repairs, or up to $500 to cap an abandoned well.

Experts urge all users of private wells to have them tested at least annually. Even if wells meet modern construction standards and have tested clean in the past, they can become contaminated as the water table rises or falls and conditions change above them. A faulty septic system or overapplication of fertilizer or pesticide can quickly taint groundwater.

Too many residents assume everything is fine “as long as the water is coming out of the tap and it doesn’t smell funny,” said Sydney Evans, a senior science analyst for the Environmental Working Group, a national advocacy organization that studies water pollution.

The main concerns vary, depending on an area’s geology and industries.

In Midwestern farming regions, for example, primary contaminants include bacteria and nitrates, which can be present in agricultural runoff. In rural Nevada and Maine, arsenic and uranium often taint water. And, throughout the country, concerns are rising about the health effects of PFAS chemicals, widely used products also known as “forever chemicals.” A recent federal study estimated at least 45% of U.S. tap water contains them.

Filters can help ensure safety, but only if they’re selected to address the specific problem affecting a home’s water supply, Evans said. The wrong filter can give a false sense of safety.

Evans said people who wonder about possible contaminants in their area can ask to see test results from wells supplying nearby community water systems. Those systems are required to test their water regularly, and the results should be public, she said: “It’s a great place to start, and it’s free and easy.”

She also said people who rely on private water wells should ask local health officials about eligibility for help paying for testing and possible repairs or filters. Subsidies are often available but not publicized, she said.

A study by Emory University researchers published in 2019 found that all states have standards for new well construction, and most states require permits for them. However, the researchers wrote, “even in states with standards for water quality testing, testing is typically infrequent or not conducted at all.”

Some longtime rural residents live in homes that have been in their families for generations. They often know little about their water source. “They’ll say, ‘This is the well my grandfather dug. We’ve used it ever since, and no one’s had an issue,’” said David Cwiertny, director of the University of Iowa’s Center for Health Effects of Environmental Contamination. They might not realize impure water can harm health over time, he said.

Some states require inspection and tests of private wells when properties are sold. Iowa doesn’t mandate such measures, although Webster County does. It’s a good idea for homebuyers anywhere to request them, said Erik Day, who oversees the private well program for the Iowa Department of Natural Resources. He also recommends asking for a technician who can run a flexible scope down the well to visually inspect the inside.

Day estimated fewer than 10% of Iowa’s private well owners have them tested annually, even though testing can be free under the state grant program.

In Webster County, Larry Jones recently took advantage of free well testing at a weathered ranch house he bought west of Fort Dodge, in a subdivision bordering a large soybean field. Jones lives next door to the 54-year-old home, and he is refurbishing it as a place for his relatives to stay.

Roderick, the county health official, sampled water from the well and found it was tainted with bacteria. She offered Jones $1,000 from the state grant to help get it fixed. He added a few thousand dollars of his own and hired a contractor.

“It’s an investment for the future,” he said. “You’re talking about your family.”

The old well was made with a 2-foot-diameter concrete casing sunk vertically in sections about 60 feet into the ground. A smaller plastic pipe ran down the middle of the casing to water at the bottom. A pump pulled water up through the smaller pipe and into the home.

Lynn Rosenquist, who owns a local well-repair business, told Jones the well probably was original to the house and likely met standards when it was built. But at least one chunk of concrete had broken off and fallen in.

Repairs took two days of heavy work by Rosenquist and his brother, Lanny, who are the third generation of their family to maintain wells. The brothers used a backhoe and small crane to remove much of the concrete casing. They replaced it with a narrower, PVC pipe, which they sealed with a cement mixture to prevent seepage from the surface. When finished, they “shocked” the system with a bleach solution, then flushed and tested again.

Such modern construction is less prone to becoming tainted, Roderick said. “If it’s not sealed airtight, bacteria can get in there and it’s just gross,” she said.

Grossness is not the only thing Roderick considers. Besides E. coli and other bacteria, she tests for nitrates and sulfates, which can exist in farm or lawn runoff or come from natural sources, and for arsenic and manganese, which can occur in rock formations. She plans to add tests for PFAS chemicals soon.

She collects the water in small plastic bottles, which she mails to a lab. She enters information about each well into a state database. If the tests turn up contaminants, she advises homeowners of their options.

Roderick said she enjoys the routine. “I’ve met so many people — and I’ve met a lot of dogs,” she said with a laugh. “I love the feeling that I’m really helping people.”

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