Iron in California well water
In California, iron was detected in 66% of 31,109 tested private well samples.
Iron is a nuisance rather than a health hazard: rust stains, metallic taste, and clogged fixtures above 300 ug/L. It often occurs with manganese and can feed iron bacteria that foul plumbing.
Check your iron 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 California well for iron
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 iron
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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 iron
Iron and manganese oxidizing filter
whole-house, at the point of entry, about $1,800
Air-injection or greensand media; fixes staining at the source.
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 iron in California: certified labs, state programs and prices.
By county, from individual samples
Public monitoring samples against the EPA limit; counties with at least 30 samples.
| County | Above EPA limit | Samples | Detected | Median | Highest |
|---|---|---|---|---|---|
| Santa Cruz | no limit | 369 | 88% | 40 | 9,200 ug/L |
| San Diego | no limit | 2,269 | 86% | 30 | 6,600,000 ug/L |
| Ventura | no limit | 632 | 84% | 41 | 33,000 ug/L |
| Santa Barbara | no limit | 4,309 | 81% | 40 | 94,000 ug/L |
| Kern | no limit | 2,282 | 77% | 20 | 400,000 ug/L |
| Mono | no limit | 459 | 77% | 33.9 | 35,000 ug/L |
| Monterey | no limit | 79 | 75% | 33 | 2,980 ug/L |
| Alameda | no limit | 1,144 | 73% | 20 | 7,800 ug/L |
| Sonoma | no limit | 373 | 70% | 20 | 30,500 ug/L |
| Imperial | no limit | 1,007 | 68% | 10.9 | 3,200,000 ug/L |
| Los Angeles | no limit | 2,134 | 68% | 4 | 14,200 ug/L |
| Santa Clara | no limit | 215 | 67% | 14.7 | 7,600 ug/L |
| Fresno | no limit | 1,109 | 66% | 20 | 170,000 ug/L |
| Tuolumne | no limit | 30 | 63% | 5.9 | 2,860 ug/L |
| San Mateo | no limit | 49 | 63% | 10 | 8,570 ug/L |
- Blythe CCD, Riverside County100% detected of 37
- Winterhaven-Bard CCD, Imperial County100% detected of 36
- Camp Pendleton CCD, San Diego County99% detected of 894
- Inglewood CCD, Los Angeles County98% detected of 55
- Mendota CCD, Fresno County98% detected of 310
- San Joaquin-Tranquillity CCD, Fresno County97% detected of 79
- West Santa Cruz CCD, Santa Cruz County97% detected of 35
- Moorpark CCD, Ventura County94% detected of 35
- Huron CCD, Fresno County94% detected of 33
- Las Posas CCD, Ventura County94% detected of 62
- Oceanside-Escondido CCD, San Diego County93% detected of 186
- Gustine CCD, Merced County93% detected of 85
- Lompoc CCD, Santa Barbara County92% detected of 1,899
- Firebaugh CCD, Fresno County92% detected of 161
- Oxnard CCD, Ventura County92% detected of 226
- Searles Valley CCD, San Bernardino County92% detected of 71
- Patterson CCD, Stanislaus County91% detected of 43
- Delano-McFarland CCD, Kern County90% detected of 72
- Camarillo CCD, Ventura County89% detected of 160
- Long Beach-Lakewood CCD, Los Angeles County88% detected of 146
Sources
- Individual samples from the USGS Water Quality Portal and state monitoring, summarized per geography. iron counts and shares are listed on each county and town page with their sources.