IOWA WATER QUALITY
Nitrate is the most talked-about drinking water issue in Central Iowa. The EPA limit is 10 mg/L (measured as nitrogen). Des Moines-area tap water has met that standard, but only because Central Iowa Water Works ran its nitrate removal facility for 193 days in 2026. Private wells get no treatment at all. Here’s what Iowa homeowners should know, and what actually reduces nitrate at your kitchen tap.
Last updated October 2026
193 days
Days the Des Moines-area nitrate removal facility ran in 2026
10 mg/L
EPA nitrate limit for drinking water (as nitrogen)
600,000+
Central Iowans served by Central Iowa Water Works
2nd
Lawn watering ban in two years, issued June 8, 2026
What Are Nitrates and Where Do They Come From?
Nitrate is a form of nitrogen that dissolves completely in water. You can’t see, smell or taste it. It moves easily through soil into rivers and shallow groundwater, especially after heavy spring rain.
In Central Iowa, most of it comes from farmland. A 2025 University of Iowa-led assessment of the Raccoon and Des Moines river watersheds found agriculture accounts for about 80% of the nitrogen in Central Iowa’s source water, with fertilizer and manure runoff as the main contributors. Those two rivers are the main water sources for the Des Moines metro.
Des Moines’ 2026 Nitrate Season at a Glance
2026 was one of the toughest nitrate years the region has seen. Here’s how it unfolded at Central Iowa Water Works, which treats water for Des Moines, Ankeny, Clive, Grimes, Johnston, Norwalk, Polk City, Urbandale, Waukee and West Des Moines.
January 6
The nitrate removal facility switched on during winter, a season when nitrate is usually at its lowest.
Early spring
All three raw water sources (the Des Moines River, the Raccoon River and the shallow groundwater gallery) were at or above the 10 mg/L standard.
June 8
A mandatory lawn watering ban took effect for the second summer in a row, because lawn watering can drive up to 40% of summer water demand.
July 23
Nitrate levels in all three sources dropped below the federal standard and the facility shut off after 193 days.
July 27
All water use restrictions ended.
Through all of it, the utility reported that treated tap water met state and federal drinking water standards. The takeaway isn’t that your tap water is unsafe. It’s that the margin depends on expensive treatment running for months at a time.
Who Should Pay Closest Attention to Nitrate?
Families with babies under 6 months
Public health agencies warn that infants under 6 months who drink water above the nitrate limit can become seriously ill from methemoglobinemia, also called blue baby syndrome. That includes water used to mix formula. If you’re expecting or have a newborn, know your water’s nitrate level.
Homes on a private well
Private wells aren’t covered by the federal Safe Drinking Water Act, so no utility tests or treats them. Nearly 300,000 Iowans rely on private wells. Shallow wells near farm fields are the most likely to run high.
Does Boiling or a Pitcher Filter Remove Nitrate?
No. This is the most common mistake we hear. Boiling actually makes nitrate more concentrated, because the water evaporates and the nitrate stays behind.
How Reverse Osmosis Reduces Nitrate at Your Kitchen Tap
A reverse osmosis system pushes water through a membrane with pores small enough to hold back dissolved substances like nitrate. The clean water goes to a dedicated faucet at your sink, and the rejected minerals and nitrate rinse down the drain.
Look for NSF/ANSI 58 certification
NSF/ANSI 58 is the national standard for home reverse osmosis systems. A system that carries the optional nitrate/nitrite claim has been tested to reduce both together. Every certified system comes with a performance data sheet that lists exactly what it was tested to reduce.
Water pressure matters
RO membranes need enough water pressure to work well. Some certified systems state their nitrate claim only applies at 40 psi or higher. We check your pressure before recommending a system.
What we see on real installs
[YOUR DATA: e.g., “Across our last 25 Central Iowa installs, total dissolved solids dropped from an average of ___ ppm at the tap to ___ ppm at the RO faucet.”]
On a Well? Iowa Offers Free Nitrate Testing
Iowa’s Private Well Grants program (formerly Grants to Counties) pays for well water testing through your county health department. Testing typically covers nitrate, coliform bacteria, arsenic and manganese. Call your county’s environmental health office and ask to be tested through the program. Test before choosing a treatment system, and retest every year.
Nitrate Questions We Hear From Iowa Homeowners
Is Des Moines tap water safe to drink with high nitrates?
Central Iowa Water Works has reported that treated water met state and federal standards throughout 2026, thanks to its nitrate removal facility. Many families still add reverse osmosis at the kitchen sink for an extra layer of protection and better taste.
Can I use tap water to make baby formula?
If you’re on city water that meets the standard, your utility considers it safe. If you’re on a private well, have it tested for nitrate before using it for formula. When in doubt, ask your pediatrician.
Does reverse osmosis remove 100% of nitrate?
No system removes everything. Certified RO systems are tested to bring nitrate well below the EPA limit under set conditions. Results depend on your water, pressure and filter maintenance.
How often should I change RO filters for nitrate?
Pre-filters are typically changed every 6 to 12 months and the membrane every 2 to 4 years, depending on your water and use. We track this for you and send reminders.
Do you serve my town?
We install reverse osmosis systems across Central Iowa, including Des Moines, Ankeny, West Des Moines, Waukee, Johnston, Urbandale, Grimes, Altoona, Ames and nearby communities.
Want Lower Nitrate Water at Your Kitchen Sink?
Tell us about your home and water source. We’ll recommend a certified system and give you a clear, upfront estimate.
Sources
Central Iowa Water Works, July 27, 2026 release
Iowa Public Radio, June 9, 2026
Iowa Capital Dispatch, June 8, 2026
University of Iowa IIHR water quality reporting
State Hygienic Laboratory: Grants-to-Counties
NSF/ANSI 58 overview