Uranium in California well water
In California, 8% of 7,553 tested private well samples exceeded the EPA limit for uranium (30 ug/L).
Uranium in well water comes from granite bedrock. Its main health effect is chemical toxicity to the kidneys rather than radiation. It is common in the same areas where radon and arsenic occur.
Check your uranium 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 uranium
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 uranium
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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 uranium
Under-sink reverse osmosis system
under-sink or countertop, about $300
Look for NSF/ANSI 58 certification listing the contaminant you need removed.
For uranium
Whole-house arsenic and uranium filter
whole-house, at the point of entry, about $2,500
Adsorptive iron-based media; sized to your well yield.
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 uranium in California: certified labs, state programs and prices.
By county, from individual samples
Public monitoring samples against the EPA limit (30 ug/L); counties with at least 30 samples.
| County | Above EPA limit | Samples | Detected | Median | Highest |
|---|---|---|---|---|---|
| Kings | 130 | 98% | 5.35 | 1,300 ug/L | |
| Fresno | 414 | 97% | 8.07 | 613 ug/L | |
| Tulare | 232 | 99% | 8.2 | 5,600 ug/L | |
| Merced | 177 | 95% | 4.4 | 270 ug/L | |
| Madera | 189 | 95% | 2.56 | 655 ug/L | |
| Stanislaus | 278 | 99% | 8.02 | 189 ug/L | |
| Kern | 645 | 89% | 4.09 | 2,500 ug/L | |
| San Diego | 123 | 98% | 3.68 | 286 ug/L | |
| San Luis Obispo | 87 | 91% | 5.75 | 1,700 ug/L | |
| Orange | 124 | 94% | 5.82 | 312 ug/L | |
| San Bernardino | 1,240 | 98% | 4.58 | 1,470 ug/L | |
| Inyo | 81 | 100% | 4.15 | 64.4 ug/L | |
| Lassen | 30 | 100% | 0.617 | 35.8 ug/L | |
| San Benito | 55 | 85% | 1.65 | 85.4 ug/L | |
| San Joaquin | 177 | 89% | 1.27 | 94.1 ug/L |
- Selma CCD, Fresno County53% of 30
- Livingston-Delhi CCD, Merced County45% of 31
- Hanford CCD, Kings County45% of 40
- Earlimart CCD, Tulare County43% of 37
- West Kern CCD, Kern County35% of 86
- Tulare CCD, Tulare County34% of 50
- Stratford CCD, Kings County33% of 49
- Oakhurst-North Fork CCD, Madera County32% of 59
- Wasco CCD, Kern County30% of 96
- Greenfield-Panama CCD, Kern County27% of 48
- Atascadero CCD, San Luis Obispo County23% of 35
- Barstow CCD, San Bernardino County21% of 309
- Buttonwillow CCD, Kern County20% of 45
- Turlock CCD, Stanislaus County19% of 36
- Jurupa CCD, Riverside County18% of 89
- North Coast CCD, Orange County18% of 45
- Lone Pine CCD, Inyo County16% of 32
- Fresno CCD, Fresno County10% of 168
- Manteca CCD, San Joaquin County10% of 30
- Newberry Springs-Baker CCD, San Bernardino County9% of 300
Sources
- Individual samples from the USGS Water Quality Portal and state monitoring, summarized per geography. uranium counts and shares are listed on each county and town page with their sources.