Thirteen public water systems serving 2,479 people recorded 36 nitrate violations, up from 14 a year earlier. Most Iowa systems still met federal health standards.
By Hola Iowa
Iowa recorded 36 nitrate-related drinking water violations in 2025, more than twice the 14 reported a year earlier.
The violations occurred at 13 public water systems serving a combined population of 2,479. Nitrate accounted for more than 41% of the state’s 87 violations of health-based drinking water standards during the year.
Nitrate was the most frequently exceeded health standard in both 2024 and 2025. The number of affected systems increased from nine to 13, while the population served by those systems rose from 1,765 to 2,479.
The figures represent separate compliance periods in which a water system exceeded the federal nitrate limit. They do not mean that 36 different systems violated the standard or that public drinking water across Iowa was unsafe.
Nearly 99% of Iowans served by public water systems received water that met all health-based standards in 2025. Of Iowa’s 1,815 regulated public water systems, 97.36% complied with those standards throughout the year.
Four systems accounted for more than half of the nitrate violations
Four public water systems recorded 21 of Iowa’s 36 nitrate violations in 2025.
Little Brown Church in Chickasaw County had nine violations, the highest number recorded by a single system. Lazy T Campground and Lost Beach Resort, both in Delaware County, each had four.
Early Municipal Water Supply in Sac County also recorded four nitrate violations.
Early Municipal Water Supply is classified as a community water system because it serves year-round residents. The church, campground and resort are classified as transient non-community systems.
A transient non-community system provides water to at least 25 people per day for at least 60 days during the year. This category can include campgrounds, parks, restaurants, highway rest areas and other locations that serve changing groups of visitors.
Several Iowa systems with nitrate violations are installing treatment equipment or connecting to another water system to address the problem.
Related: Iowa drinking water funding will expand nitrate removal
A nitrate violation means finished water exceeded the federal limit
The federal maximum for nitrate in finished drinking water is 10 milligrams per liter when measured as nitrogen.
A public water system records a violation when a sample exceeds that limit during a monthly, quarterly or annual compliance period. Iowa classifies nitrate exceedances as acute violations because they can present an immediate health risk.
Nitrate can enter source water through commercial fertilizers, human sewage, farm animal waste and the natural decay of leaves, crop residue and other organic material.
Infants younger than 6 months face the clearest immediate risk from drinking water above the federal limit. Nitrate can interfere with the blood’s ability to carry oxygen and cause methemoglobinemia, commonly called blue-baby syndrome.
Symptoms can include shortness of breath and a blue tint to the skin. Iowa health guidance warns that boiling contaminated water does not remove nitrate and can increase its concentration as water evaporates.
Researchers continue to examine possible links between long-term nitrate exposure and reproductive problems or some cancers. Iowa Health and Human Services says those studies have not established a conclusive connection, while the current federal limit is primarily designed to protect infants from acute illness.
Related: New Iowa report links pesticides and nitrates to cancer rates
Central Iowa Water Works did not record a nitrate violation in 2025
Central Iowa Water Works was not among the public systems with nitrate violations in 2025, despite unusually high nitrate concentrations in the Des Moines and Raccoon rivers.
The regional authority used its nitrate removal facility and water-use restrictions to keep finished drinking water within state and federal standards.
The system serves more than 600,000 people in Des Moines and surrounding urban, suburban and rural communities.
Elevated nitrate levels have continued to strain the regional system in 2026. Central Iowa Water Works imposed a mandatory lawn-watering ban on June 8 and later moved to less restrictive Stage II measures.
As of July 9, businesses and government agencies remained prohibited from using irrigation systems. Residential customers could water on an even-odd schedule, while the utility continued operating advanced treatment to keep drinking water within regulatory limits.
The current restrictions are tied to treatment capacity and nitrate levels in the water sources, not to a nitrate violation in the treated water delivered to customers.
Related: Central Iowa bans lawn watering as nitrates strain water system
Missed nitrate tests are counted separately from contamination violations
Iowa also recorded 84 major nitrate monitoring violations at 66 public water systems in 2025.
A monitoring violation does not establish that nitrate exceeded the federal drinking water limit. It means the system failed to collect, analyze or report a required sample during a compliance period.
Public water systems recorded 863 major monitoring and reporting violations involving multiple contaminants and administrative requirements. The largest category was failure to collect required coliform bacteria samples, with 249 violations at 158 systems.
A system can usually resolve a monitoring violation by completing the required testing, submitting the results and notifying the public. An ongoing health-based violation may require new treatment equipment or a connection to another water provider.
The statewide report does not cover private wells
More than 3.12 million Iowans, or about 94.5% of the state population, received water from a regulated public system in 2025.
The remaining population relied on private water supplies, including household wells. Those wells are not regulated or routinely monitored under the federal rules that apply to public water systems.
Iowa Health and Human Services recommends testing private wells for nitrate and coliform bacteria each year. Testing may be available at no cost through Iowa’s Private Well Grants Program, depending on participation and funding in the well owner’s county.
Residents who use private wells can contact their county environmental health office for information about testing or request a sampling kit through the State Hygienic Laboratory at the University of Iowa.
The 2025 compliance report covers only public water systems and therefore does not measure nitrate exceedances in private household wells.
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