This segment is part of The State of Science, a series featuring science stories from public radio stations across the United States. This story by Brian Grimmett originally appeared on KMUW in Wichita and the Kansas News Service.

WICHITA, Kansas — About 150,000 people in Kansas get their drinking water from private wells.

How clean, and safe, is that water? Short answer: It depends.

But new research suggests those wells deliver water tainted with a range of pollutants. Some leaked from dry cleaning operations. Yet far more wells soak up, and deliver to taps, fertilizer that’s been building up in Kansas soil and water over generations of modern farming.

But it’s not up to regulators from Washington or agencies in Topeka to test private well water quality. That falls to individual well owners. With little to no government oversight, some public health officials worry that’s creating a system where far too many people are left vulnerable to potential cancer-causing pollutants and toxins.

New research from Kansas State University shows that groundwater quality in the  Great Bend Prairie aquifer in south-central Kansas rates far worse today than 30 years ago.

The main culprit is a dramatic increase in the amount of nitrate. It’s a byproduct of the Green Revolution of the 1960s that turbo-charged modern farming toward greater yields, especially the use of chemical fertilizers.

Farmers learned that soil laced with extra nitrogen could squeeze more  bushels from an acre of land. But not all that nitrogen stays put or gets absorbed in wheat, corn, sorghum and soybeans. Some runs off into streams, or trickles into underground reservoirs.

“The change that we see is comparable to the most extreme change measured by a nationwide study,” Matthew Kirk, associate professor of geology at Kansas State University, said. “So this is a pretty big increase in nitrate.”

High levels of nitrogen in water can lead to shortness of breath. It can even cause death in young children and older adults. The federal Safe Drinking Water Act, which only governs public drinking water, limits nitrate levels to less than 10 milligrams per liter.

When Kirk sampled the water for his research, seven of the 22 wells tested exceeded that limit.

When analyzing the molecules, Kirk said it was clear that the nitrogen was coming from fertilizer leaching into the aquifer from the surface. This particular part of the natural underground reservoir is more vulnerable to land use changes because it’s relatively close to the surface, so the water doesn’t get filtered well. Kirk said it could stand as an early warning for other deeper parts of the broader High Plains aquifer.

Kirk said private well users need to test their water regularly or put the health of their families at risk.

“We do that for municipal water supplies. But for rural well owners, it’s entirely up to them,” he said. “They don’t have to have their water tested unless they want to.”

Because there’s no reporting requirement, there’s also no statewide record of groundwater quality. And even if collecting that kind of data helped officials understand the bigger picture, the movement of water underground is complex. Just because one well is contaminated doesn’t mean the next well over is too.

The National Ground Water Association recommends private well owners do a basic quality test for bacteria and nitrates once a year.

“(But) some people tend to overlook it,” said Brian Snelten, the NGWA president-elect. “It’s one of those things you can forget about. It’s like changing your car oil.”

While a basic test is going to be fine in most cases, there are other chemicals some people need to worry about.

Dry Cleaning Plume

The water in Randi Williams’ house now comes from the city of Wichita. But until a few years ago, she got her water from a private well.

“The lady that sold us the house had us taste the water and hold it up to the light,” Williams said. “And then we had it tested on our own. Since it tested fine, no problems.”

It wasn’t fine.

A toxic plume of dry cleaning chemicals had made its way to their well. It had likely been there for years.

Why didn’t she discover it when she bought the house? Because the toxic chemicals from the dry cleaning plume are odorless and tasteless, and basic tests for bacteria don’t expose it.

She wished she would have been more informed about the potential dangers near her well, such as dry cleaners and underground gas storage tanks.

“Had we known, we probably would have done more testing because, of course, we want to be healthy,” she said.

Databases of some of that information exist, but there’s no system to alert people with water wells nearby. Even if someone did know where to find the information, the average homeowner isn’t likely to understand what they’re looking at.

Knowledge Gaps

Meridian Labs in Wichita is one of a few places that offers comprehensive residential water testing in Kansas. Their tests range anywhere from $20 for a simple bacteria test, to $150 for a more comprehensive report.

“A lot of times, I will take them through their report step-by-step,” Jessica Jensen, the lab’s technical director, said. “Some people just need that peace of mind.”

Even when well owners discover there’s a problem, the cost of solving it can vary wildly. A sophisticated home filtration system could run several thousand dollars. While cleaning up a large plume, which involves the city or state, can cost several hundred thousand, even millions of dollars.

Elizabeth Ablah researches population health at the University of Kansas School of Medicine in Wichita. She said that knowledge gap is a big part of the problem. Without some kind of standardized statewide regulations, it’s too much to expect regular people to fully grasp complex water quality issues.

“We need to be starting to address these issues in a more systematic way rather than this piecemeal patchwork sort of intervention that we’ve been doing,” she said.

She and her colleague, Jack Brown, worked with state agencies, local public health officials and engineering and drilling firms to develop 18 recommendations for improving and protecting well water quality.

The recommendations range from changes in code that would standardize the definition of a nonpublic household water well to defining trigger events for when the state would require well testing.

But they were released a year ago, and so far, nothing has changed.

Ablah’s worried that without some kind of change, the Kansans with private water wells will have to continue relying largely on faith that their water is safe to drink.

“Really there’s no entity that is currently focusing on water quality for non-public water well users,” she said. “And that is a problem.”

Brian Grimmett reports on the environment, energy and natural resources for KMUW in Wichita and the Kansas News Service. You can follow him on Twitter @briangrimmett or email him at grimmett (at) kmuw (dot) org. The Kansas News Service is a collaboration of KCUR, Kansas Public Radio, KMUW and High Plains Public Radio focused on health, the social determinants of health and their connection to public policy.