Guide · Updated 2026-09-01

Nitrates in Iowa Well Water

Nitrate is common in Iowa private wells and invisible in the glass. Get a certified-lab number before anyone sells you a tank.

Nitrate does not rust a sink. It does not smell like a bad anode. Iowa DNR’s well-testing page and the State Hygienic Laboratory at the University of Iowa both treat it as an annual test because you will not see it in the glass. Private wells are not public water systems. EPA’s private-wells pages and CDC’s well-testing guidance say the owner is the utility. This page does not interpret a lab number as a health score, does not design a treatment train, and does not rank a brand. Bacteria on the same sheet still goes to the county health department first.

Get a certified-lab nitrate result first

Start at this site’s Iowa certified-lab inventory. Confirm the lab currently holds a drinking-water nitrate field in Iowa DNR LabCert PublicSearch. Certification in Iowa is by analyte and method, not by a van with a water-drop logo. Then call about bottles. SHL says the nitrate bottle is not the coliform bottle: the white powder in a bacteria vial can interfere with the nitrate test. Ask for the untreated kitchen cold tap unless the lab tells you otherwise.

Iowa DNR’s Private Well Grants cadence is annual bacteria / E. coli / coliform and nitrate, and arsenic plus manganese every three years. SHL’s private-well page matches the annual pair and says arsenic and manganese at least once in the life of the well. CDC’s well-testing guidance is the federal annual floor: total coliform, nitrates, total dissolved solids, and pH, using a state-certified lab. ISU Extension’s private-well testing page points owners to SHL kits when the county path is not the first stop.

A store strip is a screen. It is not a certified nitrate method. Well water test kits explains that split. If you want a mail-in panel while you wait on an Iowa lab, Tap Score and SimpleLab are official public URLs labeled application pending. There is no tracking tag on those links. See the disclosure.

If bacteria or nitrate is at or above the comparison number on this page, take the sheet to the county health department. Then read how to read a lab report. This site will not turn either line into a shopping list.

Compare the number to 10 mg/L as N

EPA’s National Primary Drinking Water Regulations table lists nitrate (measured as nitrogen) with an MCLG and an MCL of 10 mg/L, and nitrite (measured as nitrogen) with an MCLG and an MCL of 1 mg/L. The same table lists sources as runoff from fertilizer use, leaking septic tanks and sewage, and erosion of natural deposits. For infants below six months, the table’s language is that water above the nitrate MCL could cause serious illness and, if untreated, death, with shortness of breath and blue-baby syndrome among the symptoms listed. That is EPA’s public-system table, quoted as attribution. This site does not add a risk lecture. Questions about an infant, formula, or a household result belong with the county health department, SHL, or Iowa DNR — not a filter cart.

Iowa DNR states that private wells do not fall under mandated state or national water quality standards, and that owners should use EPA’s public-supply contaminant standards as the recommended standards for a private supply. Do not call 10 mg/L as N a private-well legal limit. It is the comparison number DNR tells you to use, and it matches the public-system MCL people already know.

Units trip people. EPA measures nitrate as N (nitrogen). Some sheets print nitrate as NO₃. Those are not interchangeable numbers. Ten milligrams per liter as nitrogen is the MCL. Ten milligrams per liter as nitrate ion is a different quantity. Ask the lab which unit they used before you compare anything to 10. If the reporting limit sits at or above 10 mg/L as N, you bought a test that cannot tell you whether you are under the recommended line.

Nitrite is its own line. The public-system MCL is 1 mg/L as N. A nitrate number is not a nitrite number.

What Iowa / USGS numbers mean — and what a map does not

USGS Water-Resources Investigations Report 2000–4106 (Sadorf and Linhart) sampled 32 domestic wells in shallow alluvial aquifers of the eastern Iowa basins (Wapsipinicon, Cedar, Iowa, and Skunk) in June–July 1998. Nitrite plus nitrate nitrogen showed up in 53 percent of those samples and exceeded 10 mg/L in 13 percent. Concentrations were negatively correlated with well depth: shallower wells ran higher. That is 32 owner wells in four basins, not a census of Iowa, not a county ranking, and not your kitchen tap.

USGS Water-Resources Investigations Report 99–4246 sampled monitoring wells — 31 agricultural sites and 30 urban sites — in the same eastern Iowa basins study unit in June–August 1997. Nitrate exceeded 10 mg/L as N in 39 percent of the agricultural-area samples. None of the urban-area samples in that set exceeded the MCL. Those were monitoring wells screened to study land use and hydrogeology, not a round of kitchen-tap bottles. Do not read “urban 0 percent” as a city-water guarantee for a farmhouse well, and do not read “39 percent” as a brand of filter you should buy.

A map of those study units is a research figure. It does not rank counties. Your well is a hole in a specific aquifer. The only number that counts is the certified-lab result from that hole.

Private Well Grants — we do not run the kit program

Iowa DNR’s Private Well Grants Program funds free testing for the annual bacteria and nitrate pair, and for arsenic and manganese on the three-year cadence, through county environmental health. DNR’s well-testing page is the program page. The published contacts — county environmental health, DNR Private Well Program, Laboratory Certification, and SHL — are already on the Iowa lab inventory. Hours change. Call before you drive.

This site does not collect samples. It does not mail kits. It does not decide whether your county still has grant money this month. ISU Extension’s private-well testing page also points to SHL when you need a kit path. Use the county office or SHL. Do not send a lab report to Well Diagnosis.

Treatment class only after a sheet

Do not shop a tank because a USGS map is orange, or because a neighbor’s well was high last spring. After you have a number, SHL names three treatment classes that can remove nitrate: distillation, reverse osmosis, and anionic exchange (ion exchange). Those are classes. Look a model up in the NSF drinking-water treatment unit database. NSF is a claim on a listed model, not a badge this site awards. Do not rank brands.

If bacteria is present, stop. County health department first. A nitrate cartridge on a contaminated well is the wrong Monday. SHL’s short-term nitrate language is an alternative source known to be safe — bottled water or a public supply — while you sort the well. Long-term, SHL puts eliminating the entry pathway ahead of a device, then names those three classes if treatment is what remains.

A nitrate class still has to sit in a sane treatment order after the pressure tank. Iron, hardness, and sediment on the same sheet change what can live upstream of an RO membrane or an anion bed. A fouled unit is how a class fails. Iowa DNR tells people with an unsafe result to talk to a DNR-certified well contractor about the well itself, not only about a tank in the basement.

Bottom line

Nitrate is common in Iowa private wells and invisible in the glass. Order a certified-lab nitrate test from the Iowa inventory. Compare milligrams per liter as N to EPA’s 10. If you are at or above that number, or you cannot read the units, take the sheet to the county health department. Treatment class comes after the sheet. Bacteria still goes to the health department. See also the homepage after you have a number, and the disclosure for affiliate status.