Nitrate in Arizona well water
In Arizona, 26% of 20,963 tested private well samples exceeded the EPA limit for nitrate (10 mg/L).
Nitrate reaches wells from fertilizer, septic systems and manure. Above the limit it can cause methemoglobinemia (blue baby syndrome) in infants under six months, and long-term exposure is associated with some cancers. Shallow and dug wells near farmland or dense septic systems are most at risk.
Check your nitrate number
Type the value from your lab report. It is compared to the EPA limit, the same way the full interpretation does it.
Test your Arizona well for nitrate
Certified lab analysis of your own tap water, bottles and prepaid return shipping included. The Essential well panel covers arsenic, uranium, nitrate, lead, copper, manganese, iron, sodium and bacteria; radon and PFAS are add-ons.
Order the Tap Score well water test kit, from $209Already tested? Upload the report
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Systems that remove nitrate
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Some links below are affiliate links. If you buy through one, the merchant pays us a commission at no extra cost to you. It does not change which products we list or what the data says.
For nitrate
Under-sink reverse osmosis system
under-sink or countertop, about $300
Look for NSF/ANSI 58 certification listing the contaminant you need removed.
For nitrate
Aquasana SmartFlow reverse osmosis
under-sink or countertop, about $225
Certified to NSF/ANSI 58 and 53 to reduce arsenic (96%, pentavalent), fluoride (90%), lead (99%), nitrate, nitrite and PFOA/PFOS at the kitchen tap, with a remineralizer.
Rather have it installed and sized for your well? Book a free in-home water test with a licensed local company.
Where to get a well tested for nitrate in Arizona: certified labs, state programs and prices.
By county, from individual samples
Public monitoring samples against the EPA limit (10 mg/L); counties with at least 30 samples.
| County | Above EPA limit | Samples | Detected | Median | Highest |
|---|---|---|---|---|---|
| Maricopa | 8,723 | 99% | 9.4 | 945 mg/L | |
| Pinal | 1,246 | 99% | 5 | 220 mg/L | |
| La Paz | 649 | 96% | 5.02 | 255 mg/L | |
| Mohave | 1,184 | 86% | 2.1 | 190 mg/L | |
| Graham | 326 | 85% | 1.5 | 150 mg/L | |
| Yuma | 673 | 75% | 0.7 | 186 mg/L | |
| Pima | 1,688 | 94% | 2 | 690 mg/L | |
| Santa Cruz | 180 | 99% | 1.57 | 47.7 mg/L | |
| Cochise | 1,024 | 98% | 1.2 | 62 mg/L | |
| Yavapai | 1,512 | 90% | 1.2 | 50.3 mg/L | |
| Navajo | 1,310 | 84% | 0.84 | 770 mg/L | |
| Coconino | 863 | 93% | 0.598 | 1,700 mg/L | |
| Gila | 354 | 79% | 0.985 | 55.2 mg/L | |
| Apache | 1,141 | 83% | 0.223 | 97 mg/L | |
| Greenlee | 90 | 98% | 1 | 22 mg/L |
- Phoenix CCD, Maricopa County54% of 6,185
- Florence CCD, Pinal County46% of 137
- Buckeye CCD, Maricopa County46% of 766
- Chandler CCD, Maricopa County45% of 462
- Eloy CCD, Pinal County37% of 300
- Casa Grande CCD, Pinal County37% of 132
- Maricopa-Stanfield CCD, Pinal County34% of 181
- Salt River CCD, Maricopa County32% of 130
- Tohono O'odham Nation CCD, Pinal County32% of 44
- St. Johns CCD, Maricopa County32% of 73
- Parker CCD, La Paz County29% of 649
- Pima CCD, Graham County28% of 101
- Ajo CCD, Pima County22% of 91
- Wellton CCD, Yuma County21% of 326
- Marana CCD, Pima County20% of 144
- Benson CCD, Cochise County19% of 198
- Coolidge CCD, Pinal County19% of 131
- Deer Valley CCD, Maricopa County18% of 179
- Gila Bend CCD, Maricopa County18% of 616
- Lake Havasu City CCD, Mohave County18% of 353
Sources
- Individual samples from the USGS Water Quality Portal and state monitoring, summarized per geography. nitrate counts and shares are listed on each county and town page with their sources.
Analysis: Nitrate in private wells, decade by decade, from the same public records.