Well water in Santa Barbara County, California

Name: Private well water quality in Santa Barbara County, California
Creator: Well Water Nerd
License: Public domain (US federal government data)

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Testing strongly recommended

tested well samples in Santa Barbara County exceeded the EPA limit for E. coli (0 MPN/100mL), based on public data from USGS Water Quality Portal.

The strongest signal is PFOS: 22% of 18 local samples were above the limit, too few samples to carry the headline but first on the test list below.

30,687 test results across 14 contaminants from at least 1,412 wells, 1924 to 2026; nitrate has the most at 8,473. Data refreshed September 15, 2026.

Compiled by Nick at Well Water Nerd from public records. How these pages are built

An estimated 7,976 people in Santa Barbara County get their drinking water from a private well, per USGS 2015 county water use. That is about 2% of residents.

Separately, the USGS national arsenic model estimates that 33% of the 7,976 people on private wells in Santa Barbara County draw water above 10 ug/L (the model's range is 24% to 44%), from geology and well depth rather than local tests.

What individual samples found

Each row summarizes every public sample for that contaminant inside Santa Barbara County. Above limit means above the EPA maximum contaminant level; where EPA has no enforceable limit, the row shows a health guideline or nuisance level instead.

Contaminant	Above limit	Samples	Detected	Median	Highest	Limit
PFOS 2021 to 2023	22%	18	39%	0	160	4 ng/L EPA limit
E. coli 2005 to 2007	21%	63	21%	0	1,300	0 MPN/100mL EPA limit
Nitrate 1927 to 2026	15%	8,473	72%	0.678	460	10 mg/L EPA limit
PFOA 2021 to 2023	6%	18	17%	0	300	4 ng/L EPA limit
Arsenic 1958 to 2025	5%	539	83%	0.62	67.1	10 ug/L EPA limit
Lead 1954 to 2023	1%	339	44%	0	100	15 ug/L EPA limit
Uranium 2008 to 2025	<1%	211	89%	2.07	75.2	30 ug/L EPA limit
Fluoride 1941 to 2025	<1%	6,069	97%	0.3	13	4 mg/L EPA limit
Copper 1954 to 2023	<1%	354	50%	0	1.4	1.3 mg/L EPA limit
Radium (226 + 228) 2017 to 2022	0%	136	71%	0.1	2.8	5 pCi/L EPA limit
Sodium 1924 to 2025	no limit	6,873	100%	94	11,200	20 mg/L health guideline
Iron 1924 to 2025	no limit	4,309	81%	40	94,000	300 ug/L nuisance level
Manganese 1943 to 2025	no limit	3,264	89%	71	25,000	300 ug/L health guideline
Radon 2011	no limit	21	100%	760	1,990	2,000 pCi/L health guideline

Over time

Share of samples above the limit by period. A cell needs ten samples to show; a comparison needs twenty in each period. Later periods sample fewer wells, and often the ones already known to have a problem.

Contaminant	before 2000	2000s	2010s	2020s
Nitrate	16%5,214 samples	9%1,429 samples	17%1,487 samples	13%343 samples
Fluoride	<1%4,488 samples	2%647 samples	<1%764 samples	<1%170 samples
Arsenic	9%117 samples	13%46 samples	4%291 samples	2%85 samples
Copper	<1%162 samples	0%34 samples	0%133 samples	0%25 samples
Lead	3%146 samples	0%34 samples	0%134 samples	0%25 samples
Uranium	n/a	0%34 samples	1%134 samples	0%43 samples

Nitrate, fluoride, arsenic, copper, lead, uranium have held within a few points between the two most recent periods with enough samples.

Closer than the county

See the sampled wells near your address

The same records, drawn around one point: which wells within a few miles were sampled and what they found, how deep the wells next to you were drilled, and any leaking tank or cleanup site within a mile.

Check my address

What this means

The contaminants most often above their limit here are pfos (22% of 18 samples), e. coli (21% of 63 samples), and nitrate (15% of 8,473 samples). A well next door can differ sharply from yours because bedrock fractures, well depth and plumbing all matter, so these rates describe the area, not your tap.

Iron and Manganese are widespread in local groundwater. They are mainly a staining and taste problem, but high manganese also carries a health advisory for infants.

What to test for in Santa Barbara County

1
PFOS
22% of 18 local samples were above the limit.
2
E. coli
21% of 63 local samples were above the limit.
3
Nitrate
15% of 8,473 local samples were above the limit.
4
PFOA
6% of 18 local samples were above the limit.
5
Arsenic
5% of 539 local samples were above the limit.
6
Lead
1% of 339 local samples were above the limit.
7
Uranium
<1% of 211 local samples were above the limit.
8
Volatile organic compounds (VOCs)
930 leaking underground storage tank sites on record locally.
9
Metals panel
8 hazardous waste sites on record locally.

Test your Santa Barbara County well for PFOS, E. coli and 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 $209 Already tested? Upload the report

Just want bacteria checked first? Tap Score coliform and E. coli test, $99. Coliform and E. coli are the tests every well needs every year.

Want a quick look before paying for a lab? Home well water test strips on Amazon check hardness, iron, pH and nitrate in minutes. They are a screen, not a result: arsenic, bacteria, uranium and PFAS need a certified lab.

Affiliate links: the merchant pays us a commission and the price is the same for you. It does not change what the data above says. As an Amazon Associate we earn from qualifying purchases.

Where to get a well tested in California: certified labs, state programs and prices.

Already have results back? Get your lab report read against the Santa Barbara County numbers, $29. Every line explained, ranked by what matters, with the fix for each.

The rock under Santa Barbara County

Not a principal aquifer

The USGS map places this area outside any principal aquifer, which usually means wells here draw from fractured bedrock or thin local deposits rather than a large regional aquifer. Bedrock wells of that kind are where arsenic, radon and uranium turn up, and yields vary from well to well.

Classification from the USGS Principal Aquifers of the United States (national map, 2003 edition, GIS release 2015), read at the county centroid. A single well can sit in a different unit, especially near a boundary.

Official help in California

Two places to start that are not selling anything: the state program that answers private well questions, and its list of labs certified to run drinking water tests. A certified lab is the difference between a result you can act on and a number.

GAMA - Well Owners, State Water Resources Control Board
Environmental Laboratory Accreditation Program (ELAP), State Water Resources Control Board

Contamination sources on record in Santa Barbara County

California GeoTracker and EnviroStor sites records 930 leaking underground storage tank sites and 8 hazardous waste sites in Santa Barbara County, among 1,868 regulated sites in total. Groundwater does not follow property lines, so a well within a few hundred feet of one of these is worth testing for what that site could release.

930: leaking underground storage tank sitesGasoline and heating oil that leaked from tanks move through groundwater as benzene, MTBE and other volatile organic compounds.
8: hazardous waste sitesSolvents, degreasers and metals from industrial sites can travel far in fractured bedrock.
34: lined landfills and transfer facilities
896: other remediation projects

Treatment that fits the local profile

PFOS

Granular activated carbon whole-house; Point-of-use reverse osmosis; Anion exchange

E. coli

Shock chlorination and fix the well cap or casing; UV disinfection whole-house; Chlorination system

Nitrate

Point-of-use reverse osmosis; Anion exchange; Distillation

PFOA

Granular activated carbon whole-house; Point-of-use reverse osmosis; Anion exchange

Arsenic

Point-of-use reverse osmosis; Adsorptive media (iron-based) whole-house; Anion exchange

Systems we would look at first

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 PFOS

Under-sink reverse osmosis system

under-sink or countertop, about $300

Look for NSF/ANSI 58 certification listing the contaminant you need removed.

For PFOS

Whole-house PFAS carbon system

whole-house, at the point of entry, about $3,000

Granular activated carbon certified to NSF/ANSI 53 for PFOA and PFOS; replace media on schedule.

For PFOS

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.

For E. coli

UV disinfection system

whole-house, at the point of entry, about $900

Fix the well cap and casing first; UV keeps bacteria from returning.

For E. coli

Aquasana Rhino Well Water with UV

whole-house, at the point of entry, about $2,871

Whole-house system built for wells: sediment pre-filter, KDF and carbon, and a UV lamp rated to kill 99.99% of bacteria and viruses. It does not remove arsenic, nitrate, uranium or radon.

For PFOA

Aquasana Claryum 3-Stage under-sink filter

under-sink or countertop, about $175

Certified to NSF/ANSI 53 to reduce 99% of lead and 99.7% of PFOA and PFOS at the tap. Not a fix for arsenic, nitrate or bacteria.

For PFOA

Aquasana HealthShield whole-house filter

whole-house, at the point of entry, about $2,099

Whole-house carbon system the maker certifies to reduce PFAS (PFOA and PFOS) and VOCs at every tap; a UV option adds bacteria protection.

Free, no obligation

Get on the list for a free in-home water test in Santa Barbara County

No water treatment company serves Santa Barbara County through Well Water Nerd yet. We are signing licensed companies on county by county: they test at your tap for free, walk you through the numbers, and quote treatment only if something needs fixing. Leave your details and you are first in line. Nothing is shared until a company joins for Santa Barbara County, and you get an email naming it first.

Common questions

Is there arsenic in well water in Santa Barbara County?

Arsenic was detected in 83% of 539 public well samples in Santa Barbara County, and 5% were above the EPA limit of 10 ug/L. Arsenic has no taste or smell; a lab test is the only way to know your level.

How high is radon in well water in Santa Barbara County?

The median radon level across 21 public samples in Santa Barbara County was 760 pCi/L, with a high of 1,990 pCi/L. New Hampshire recommends treatment above 2,000 pCi/L.

How often should I test a private well in Santa Barbara County?

Test for bacteria and nitrate every year. Test once for arsenic, uranium, radon, fluoride, manganese and PFAS, then again every three to five years or after any change in taste, color, or plumbing.

Counties near Santa Barbara County

Closest first. Groundwater does not stop at a line on a map, so the next county over is a fair second opinion.

Want the numbers themselves? Download the California dataset as CSV, every county and town, with the sources named.

Sources

USGS Water Quality Portal: 30,687 samples in Santa Barbara County. Data from the Water Quality Portal, a service of USGS, EPA and USDA; groundwater samples collected by USGS and cooperators. Retrieved September 3, 2026.
USGS national arsenic model (Ayotte 2017): estimated share of 7,976 people on private wells in Santa Barbara County above 10 ug/L of arsenic, from geology, well depth and land use. County estimates of domestic well users with arsenic above 10 ug/L from the USGS national logistic regression model (Ayotte, Medalie and Qi, 2017), with private well population from the USGS 2015 county water-use compilation (Dieter and others, 2018). Retrieved September 15, 2026.
California GeoTracker and EnviroStor sites: 1,868 regulated sites located in Santa Barbara County. Leaking underground storage tank and cleanup sites from the State Water Board GeoTracker export on data.ca.gov, and DTSC EnviroStor cleanup sites. Retrieved September 15, 2026.

Non-detects count as samples and are treated as zero when computing medians. Exactly at the limit counts as not above it. A sample belongs to the town containing the well's reported coordinates.