Thirteen public water systems serving 2,479 people recorded 36 nitrate violations in 2025, up from 14 a year earlier. Nearly 99% of Iowans served by public systems still received water that met all health-based standards.
By Hola Iowa
Updated Friday, Aug. 7, 2026.
Iowa public water systems recorded 36 nitrate violations in 2025, more than twice the 14 reported a year earlier.
The violations occurred at 13 systems serving a combined population of 2,479, according to the Iowa Department of Natural Resources’ 2025 drinking water report.
The increase does not mean that drinking water across Iowa was unsafe. The 36 violations represent separate compliance periods, not 36 different water systems.
Is my water safe? What Iowa residents should know
- Most public water met health standards: About 98.91% of Iowans served by regulated public systems received water from systems that complied with all health-based standards in 2025.
- Nitrate violations were limited to 13 systems: Those systems served a combined population of 2,479.
- Central Iowa Water Works: The regional system did not record a nitrate violation in 2025 and returned to normal Stage 0 conservation practices on July 27, 2026.
- Private wells: The state report does not include household wells. Iowa recommends testing them for nitrate and coliform bacteria every year.
- Do not boil water to remove nitrate: Boiling can increase the nitrate concentration as water evaporates.
- Check your provider: The report covers 2025. Residents can review current notices from their water provider or search the Iowa DNR public drinking water database.
Most Iowa public water systems met health standards
Nitrate accounted for more than 41% of Iowa’s 87 violations of health-based drinking water standards in 2025. It was the most frequently exceeded health standard for the second consecutive year.
The number of nitrate violations rose from 14 in 2024 to 36 in 2025. The number of affected systems increased from nine to 13, while the combined population served by those systems grew from 1,765 to 2,479.
Nearly 99% of Iowans served by public water systems received water from systems that met all health-based standards in 2025. Of the state’s 1,815 regulated systems, 97.36% complied with those standards.
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 serves year-round residents and is classified as a community water system. The church, campground and resort are transient non-community systems, which generally 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 nitrate limit for finished drinking water is 10 milligrams per liter when measured as nitrogen.
A public water system records a violation when its drinking water exceeds that limit during an assigned monthly, quarterly or annual compliance period. Iowa classifies nitrate exceedances as acute violations because they can create 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. Nitrate can interfere with the blood’s ability to carry oxygen and cause methemoglobinemia, commonly known as blue-baby syndrome.
Symptoms can include shortness of breath and a blue tint to the skin. Anyone who notices those symptoms should seek medical attention immediately.
Boiling contaminated water does not remove nitrate. It can increase the concentration as water evaporates. Families under a nitrate advisory should follow their water provider’s instructions and use an approved alternative water source when directed.
Researchers continue to study possible links between long-term nitrate exposure, reproductive problems and some cancers. Iowa Health and Human Services says the findings remain inconclusive and that the current federal standard primarily protects 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
Central Iowa Water Works was not among the public systems with nitrate violations in 2025, despite 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. Its member utilities and communities serve more than 600,000 people across central Iowa.
Elevated nitrate levels again strained the regional system in 2026. Central Iowa Water Works imposed a mandatory lawn-watering ban on June 8 and began easing restrictions in July as conditions improved.
On July 27, the authority returned to Stage 0, ending its mandatory and voluntary restrictions after the nitrate removal facility completed 193 days of operation.
Customers may follow the normal even-odd lawn-watering schedule. Addresses ending in an even number may water Sunday, Wednesday and Friday. Odd-numbered addresses may water Tuesday, Thursday and Saturday. The schedule does not allow lawn watering on Mondays.
Central Iowa Water Works continues to monitor river conditions, regional demand and treated water quality. The 2026 restrictions responded to nitrate levels in source water and limits on treatment capacity; they did not indicate a nitrate violation in the finished water delivered to customers.
Current guidance is available through the Central Iowa Water Works water-use update.
Related: Central Iowa bans lawn watering as nitrates strain water system
Missed nitrate tests are counted separately
Iowa 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 involved required coliform bacteria samples, with 249 violations at 158 systems.
A system can generally resolve a monitoring violation by completing the required testing and submitting the results. A health-based violation may require treatment equipment, an alternative water source or a connection to another provider.
The statewide report does not cover private wells
More than 3.12 million Iowans received water from a regulated public system in 2025. Other residents relied on private water supplies, including household wells.
Private wells do not fall under the federal regulations and routine monitoring requirements that govern public systems. The 2025 compliance report therefore does not show whether a private household well exceeded the nitrate limit.
Iowa Health and Human Services recommends testing every private well used for drinking water for nitrate and coliform bacteria once a year.
Well owners can contact their county environmental health office for testing information. Funding may be available through Iowa’s Private Well Grants Program, depending on county participation and available resources.
Residents can also request a private-well sampling kit from the State Hygienic Laboratory. The kit includes bottles and instructions for collecting samples for nitrate and coliform bacteria testing.
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