Somewhere in rural Iowa right now, a family is filling a glass from their kitchen tap. The water is clear. It tastes fine. It might be poisoning them.
They wouldn't know. Their well has never been tested. And nobody — not the EPA, not the state, not the county — is required to tell them otherwise.
That family is not unusual. They are the norm.
The Invisible 43 Million
Approximately 43 million Americans — roughly 15 percent of the U.S. population — get their drinking water from private wells. That's more than 23 million households, concentrated in rural communities across the South, Midwest, and Appalachia, but scattered through suburbs and exurbs nationwide.
Here is the fact that should unsettle every one of them: private wells are not covered by the Safe Drinking Water Act. The landmark 1974 law that sets enforceable standards for lead, arsenic, nitrate, bacteria, and dozens of other contaminants in public water systems simply does not apply to private wells. Not partially. Not conditionally. Not at all.
Public water utilities must test regularly, report results, notify customers of violations, and meet maximum contaminant levels (MCLs) set by EPA. Private well owners are on their own. The responsibility for testing, treatment, and maintenance falls entirely on the homeowner — most of whom have no training in water chemistry and no idea what to test for.
The result is a two-tiered drinking water system: one regulated, monitored, and publicly accountable; the other essentially invisible.
What the Data Shows
The U.S. Geological Survey conducted a national assessment of approximately 2,100 private domestic wells and found that about one in five — roughly 20 percent — contained at least one contaminant at a concentration exceeding a human-health benchmark for drinking water. The most frequently detected contaminants above benchmarks were nitrate, arsenic, uranium, and manganese.
That one-in-five figure is almost certainly an undercount. It reflects wells that were actually sampled. The vast majority never are.
Survey-based syntheses of state data suggest that around 40 percent of U.S. private well owners have never tested their water at all — despite the EPA recommending at least annual testing for bacteria and nitrate. In Iowa, where roughly 300,000 residents rely on private wells, only about 6,000 — barely 2 percent — test annually for bacteria and nitrate.
The math is simple and grim. If 20 percent of tested wells fail, and 40 percent of wells have never been tested, then millions of Americans may be drinking contaminated water without knowing it.
Arsenic: The Quiet Threat
Arsenic is one of the most dangerous contaminants found in private wells because it is odorless, tasteless, and invisible. Long-term exposure to arsenic above the EPA's maximum contaminant level of 10 parts per billion (µg/L) is associated with increased risk of bladder, lung, and skin cancers, as well as cardiovascular disease and developmental effects in children.
USGS-based estimates suggest roughly 4 percent of U.S. private wells contain arsenic above the 10 µg/L standard, exposing several million people. Elevated arsenic in private well water is most prevalent in parts of New England — particularly Maine and New Hampshire — the Upper Midwest (Michigan, Minnesota, Wisconsin), the Great Plains, and the arid Southwest (Arizona, Nevada, New Mexico).
An estimated 2.7 million people are exposed to unsafe arsenic levels through private wells under normal conditions. During drought, when water tables drop and arsenic concentrations increase, that number climbs to over 4 million.
None of these people receive a violation notice. None of them see a warning on a water bill. Their wells are not in any monitoring database. They simply drink the water.
Nitrate: Agriculture's Runoff Problem
Nitrate contamination tells a different but equally troubling story. Nationwide data indicate that roughly 1 in 7 private wells — about 14 percent — have nitrate levels above the 10 mg/L drinking water standard. The primary sources are agricultural fertilizer runoff, animal manure, and failing septic systems — all of which can leach into the shallow groundwater that most private wells tap.
High nitrate levels are particularly dangerous for infants, causing methemoglobinemia — "blue baby syndrome" — a condition where the blood's ability to carry oxygen is compromised. Long-term exposure in adults is linked to thyroid disease and certain cancers.
The geographic pattern is predictable: nitrate exceedances cluster in the intensive farming regions of the Midwest, the Central Valley of California, and parts of the Great Plains. But they also appear anywhere septic systems and shallow wells coexist — which describes much of rural America.
The Patchwork of State Rules
If the federal government won't regulate private wells, what about states? The answer is: some do a little, most do almost nothing.
A 2019 peer-reviewed review of state private well policies found that while all 50 states regulate drilling and construction of new wells, far fewer require any water-quality testing. A 2024 legal policy brief from the Network for Public Health Law confirmed that "only a few states have established water quality testing requirements for private wells" — and those requirements are typically limited to narrow triggers like new well construction, property transfer, or rental situations.
The most commonly cited count identifies only about 11 states that require testing at the time of property sale or transfer: Connecticut, Delaware, Maryland, Minnesota, Nebraska, New Jersey, New Mexico, Oregon, Rhode Island, South Dakota, and Wisconsin. Three states — Connecticut, Florida, and New Jersey — require some form of testing for rental properties with private wells.
New Jersey stands out as the national leader. Its Private Well Testing Act requires sellers or buyers to test untreated groundwater for up to 33 primary and secondary drinking water parameters before closing on a property. Results must be shared with both parties and reported electronically to the state Department of Environmental Protection, which uses the data for statewide groundwater surveillance. New Hampshire enacted a law in July 2024 requiring PFAS contamination disclosure at home sale — a sign that states are beginning to reckon with emerging contaminants in private wells.
But these are the exceptions. In most states — including Georgia, Alabama, Mississippi, and much of the rural South — there is no requirement to test private well water at any point: not when you drill it, not when you sell the house, not ever.
The PFAS Dimension
The private well regulatory gap takes on new urgency in the era of PFAS. When EPA finalized national drinking water standards for six PFAS compounds in 2024, those standards applied only to public water systems. Private wells were, once again, excluded.
A 2026 USGS water quality bulletin found that about half of groundwater used for drinking water supply in the United States contains detectable PFAS. For private well owners near military bases where aqueous film-forming foam (AFFF) was used, near industrial facilities, or downstream of landfills that accepted PFAS-containing waste, the exposure risk is acute.
The contamination near Pease Air Force Base in New Hampshire illustrates the pattern. PFOS concentrations of 2,500 parts per trillion were confirmed in a nearby municipal well, and PFAS compounds including PFHxS were detected in neighboring private residential wells. Military bases across the country — from Camp Lejeune in North Carolina to Wurtsmith Air Force Base in Michigan — have left similar plumes of PFAS contamination in local groundwater. Private well owners within those plumes may have no idea they're affected unless they pay for specialized testing that can cost $300 or more per sample.
What Would It Take to Fix This?
The solutions are not mysterious. They are just unfunded and politically inconvenient.
Testing. EPA recommends that private well owners test annually for bacteria and nitrate, and for other contaminants based on local conditions. A basic bacteria and nitrate test costs roughly $30 to $60. A comprehensive panel covering metals, inorganics, and basic chemistry runs $150 to $350. These are not insurmountable costs — but they require awareness, access to certified labs, and the knowledge of what to ask for. Most rural well owners have none of these.
State programs. Some states have begun to build infrastructure around this gap. Virginia operates extension-led private well education and testing initiatives that periodically offer low-cost testing clinics subsidized by state and university funding. New Jersey's PWTA creates a statewide database of private well water quality through mandatory point-of-sale testing. These models work. They need to be replicated.
Extension services. University extension programs — including UGA Extension in Georgia — serve as the practical bridge between government regulators and rural homeowners. Extension agents provide sampling guidance, interpret results, and connect well owners to treatment solutions. But extension budgets are tight, and private well outreach competes with agricultural programming for limited resources.
Federal engagement. The Bipartisan Infrastructure Law included some funding for private well testing and treatment through state revolving funds, but the amounts are modest compared to the scale of the problem. A dedicated federal program for private well monitoring — even a voluntary one with subsidized testing — would represent a fundamental shift in how America thinks about drinking water equity.
The Principle at Stake
There is something deeply wrong with a system that tests the drinking water of apartment dwellers in Manhattan but not the well water of families in rural Georgia. The Safe Drinking Water Act was a landmark achievement, but its exclusion of private wells created a gap that has persisted for over 50 years — a gap that disproportionately affects rural communities, communities of color, and low-income households.
At the EPR Foundation, we believe that protecting people means protecting all people — including the 43 million who draw their water from the ground beneath their feet. That means state testing requirements that don't wait for a property sale. It means subsidized testing programs funded at scale. It means PFAS standards that apply to every drinking water source, not just public systems. And it means extension services with the resources to reach every county in America.
Clean water should not depend on your zip code or whether your water comes from a pipe or a pump.
If you have a private well, test your water. If your state doesn't require it, demand to know why. And if your neighbor has never tested theirs, help them find a lab.
Forty-three million people are waiting. Most of them just don't know it yet.
Sources: U.S. Environmental Protection Agency, Private Drinking Water Wells; U.S. Geological Survey, Domestic (Private) Supply Wells; Network for Public Health Law, Water Quality Testing Requirements for Private Wells (2024); New Jersey DEP, Private Well Testing Act; CDC, Private Drinking Water and Public Health; Schaider et al., "Environmental Health Perspectives" (2019).