Typical values from 222 sampled wells in Kern County · Full groundwater profile
What Kern County Wells Usually Need
Arsenic above the drinking water limit. Arsenic exceeded the 10 µg/L limit in 25% of 213 sampled Kern wells. It has no taste or smell, so only a lab test shows whether your well is affected.
Safe to drink? Only after a lab test that includes arsenic.
What usually fixes it:
- A whole-house sediment filter first, so sand and scale do not foul the stages after it.
- A 32,000-grain water softener for a family of four at 12.1 gpg (includes 5 gpg per ppm of iron).
- Point-of-use reverse osmosis for drinking water, but only after a lab test confirms the problem in your well.
See how a well water filtration system is laid out. Your own test result decides the final list.
Not sure what to install? Get a filter recommendation for Kern County homesIf your water comes from a utility, its annual Consumer Confidence Report is the right source; the figures here are for private wells. Find your utility's report
On this page (8 sections)
Where to Test Well Water in Kern County
- Your county environmental health department handles private well questions in Kern County; for a water test, use a state-accredited lab, many of which accept mailed or dropped-off samples.
- Certified labs: State Water Board list of accredited labs (ELAP)
Ask the lab for sample bottles and how quickly the sample must reach it before you collect.
What Are You Noticing in Your Water?
Pre-selected from Kern County well data. Untick anything you do not notice in your own water.
Confirm with a lab test before buying equipment.
Explore California Interactive Map
Explore Kern County and nearby counties
Kern County has about 914,000 residents, and its largest communities are Bakersfield, Delano and Ridgecrest. Homes outside city and community water systems rely on private domestic wells. Wells here tap the Central Valley aquifer system, and the largest DWR groundwater basin in the county is San Joaquin Valley – Kern County.
Across 222 sampled wells, groundwater is very hard (12.1 gpg in the typical well). Arsenic exceeded the 10 µg/L drinking water limit in 25% of 213 sampled wells. These have no taste or smell, so only a lab test shows whether your own well is affected.
In this guide
Groundwater Profile: Kern County
Across 222 sampled wells, the median hardness is 12.1 gpg (very hard). At 12.1 gpg, Kern wells run harder than Tulare (9.3 gpg), San Bernardino (7.3 gpg) and Inyo (4.5 gpg), softer than Santa Barbara (28.3 gpg), Ventura (29.5 gpg) and San Luis Obispo (31.1 gpg) and about as hard as Los Angeles (11.5 gpg) next door. The largest California DWR Bulletin 118 groundwater basins in the county are San Joaquin Valley – Kern County, Antelope Valley and Fremont Valley.
Another address? Check hardness by ZIP code.
What shows up in local well samples:
- HardnessMedian 12.1 gpg; 66% of 222 sampled wells above 7 gpg
Calcium and magnesium dissolved from limestone. Leaves scale on fixtures and water heaters and reduces soap lather. Not a health risk.
Water softener sizing - Arsenic25% of 213 sampled wells above 10 µg/L
Odorless and tasteless, with an EPA limit of 10 µg/L. Only a lab test detects it.
How to test your well
Salinity varies across the county: 31% of 206 sampled wells exceed California’s 1,000 mg/L upper limit for dissolved solids, even though the typical well (487 mg/L) is below it.
Hydrogen sulfide was above 0.1 mg/L in 8% of 113 wells tested in Kern County, so a rotten-egg smell is possible but not typical.
Arsenic, Nitrate, Chromium-6 and Salinity in Kern County
| Contaminant | Typical well | Wells above limit | California standard |
|---|---|---|---|
| Arsenic | 3.5 µg/L | 25% of 213 | 10 µg/L (primary MCL) |
| Nitrate (as nitrogen) | 0.95 mg/L | 6% of 219 | 10 mg/L (primary MCL) |
| Chromium-6 | 0.66 µg/L | 4% of 136 | 10 µg/L (primary MCL since Oct. 1, 2024) |
| Salinity (dissolved solids) | 487 mg/L | 31% of 206 | 500 mg/L recommended, 1,000 mg/L upper (secondary) |
| Hardness | 12.1 gpg | 66% of 222 | No limit; above 7 gpg is hard |
Typical well = median. Standards: State Water Board; samples: Water Quality Portal, since 2000.
How Kern County Compares to California and the U.S.
See How Kern County Compares to California & the US
| Share of wells with… | Kern CountyKern | CaliforniaCA | United StatesUS |
|---|---|---|---|
| Hard water (above 7 gpg) | 66% | 64% | 60% |
| Iron above 0.3 mg/L | 10% | 9% | 19% |
| Manganese above 0.05 mg/L | 27% | 22% | 21% |
| Dissolved solids above 500 mg/L | 50% | 38% | 15% |
| Acidic water (pH below 6.5) | <1% | 2% | 14% |
| Nitrate above 10 mg/L (EPA limit) | 6% | 9% | 4% |
| Arsenic above 10 µg/L (EPA limit) | 25% | 14% | 7% |
| Chromium-6 above 10 µg/L (California limit) | 4% | 6% | — |
| Median hardness | 12.1 gpg | 9.9 gpg | — |
| Median pH | 7.8 | 7.6 | 7.3 |
Sources: Water Quality Portal (since 2000); US: USGS Circular 1332. Highlighted: well above the US share.
See what a typical Kern County well needs
Pre-filled with the Kern medians. Swap in your own results.
Testing Your Well in Kern County
The Kern County Public Health, Environmental Health Division handles private well permits and can advise on testing. For bacteria, nitrate, arsenic or a full panel, use a laboratory accredited by California’s Environmental Laboratory Accreditation Program (ELAP); the State Water Board’s certified lab map lists them.
What to test for in Kern County:
- Bacteria (total coliform and E. coli), nitrate and arsenic, at least once a year (California State Water Resources Control Board recommendation)
- Hardness in grains per gallon (gpg) to size a softener
- Arsenic, which appeared above the 10 µg/L limit in some sampled wells here
- After any flood, new well work or a change in taste, color or smell
Which tests to order and how: how to test well water.
After a positive coliform test, shock the well with the right bleach dose and retest 10 to 14 days later.
Nearby Counties
Kern County borders these counties with published reports:
Inyo County
4.5 gpg hardness · ArsenicKings County
3.8 gpg hardness · Hydrogen sulfide, Total dissolved solidsLos Angeles County
11.5 gpg hardness · Hardness, ArsenicSan Bernardino County
7.3 gpg hardness · Hardness, ArsenicSan Luis Obispo County
31.1 gpg hardness · Hardness, Hydrogen sulfideSanta Barbara County
28.3 gpg hardness · Hardness, Hydrogen sulfideTulare County
9.3 gpg hardness · Hardness, Hydrogen sulfideVentura County
29.5 gpg hardness · Hardness, Hydrogen sulfideCounties with similar well water
Not next door, but the groundwater is much the same:
Frequently Asked Questions
Is well water in Kern County safe to drink?
Many wells are fine, but in county records arsenic exceeded the 10 µg/L limit in 25% of 213 sampled wells and nitrate exceeded the 10 mg/L limit in 6% of 219 sampled wells. Have your water tested for these and for bacteria before you drink it untreated.
How hard is well water in Kern County?
Very hard. The median Kern well tests at 12.1 grains per gallon across 222 sampled wells (California median: 9.9 gpg), and 66% are above the 7 gpg mark where most homes add a softener.
Is iron a problem in Kern County well water?
Usually not. Across 208 sampled wells the median is 0.01 mg/L, under the 0.3 mg/L stain threshold, though 10% of wells exceed it. If your fixtures stain, test for iron and manganese before buying a filter.
Is arsenic a problem in Kern County well water?
Arsenic topped 10 µg/L in 25% of the 213 wells sampled here. You cannot see or taste it, so test for it, and use reverse osmosis or an arsenic filter if your result is high.
Is nitrate a problem in Kern County well water?
In 6% of 219 sampled wells, nitrate exceeded 10 mg/L. Test before using well water for babies, and treat with reverse osmosis if your result is high.
Why does my well water smell like rotten eggs in Kern County?
Hydrogen sulfide was above 0.1 mg/L in 8% of 113 wells tested in Kern County, so a rotten-egg smell is possible but not typical. The smell is a nuisance rather than a health risk at typical levels.
Is chromium-6 a concern in Kern County well water?
Hexavalent chromium was above California’s 10 µg/L drinking water limit in 4% of 136 sampled wells in Kern County. The limit took effect on October 1, 2024. It has no taste or smell, so only a lab test shows whether your well is affected; reverse osmosis is a common household treatment.
Can I install a salt-based water softener in Kern County?
Usually, but check local rules first. California Water Code Section 13148 lets some local sewer and water recycling agencies limit or ban new salt-discharging softeners to protect recycled water. Homes on septic systems should ask the county environmental health department about brine. A salt-free conditioner discharges no brine, but it reduces scale rather than softening the water.
Does boiling well water make it safe to drink in Kern County?
No, not for the arsenic found in some Kern wells. Boiling kills bacteria, but chemicals stay behind and become more concentrated as water evaporates. Here is why boiling cannot remove nitrate or arsenic.
How often should I test my well water in Kern County?
The California State Water Resources Control Board recommends testing domestic wells every year, including for bacteria, nitrate and arsenic, and again after flooding or well repairs. The Kern County Public Health, Environmental Health Division can explain how to collect and submit samples.
Written by Well Water Advisor Editorial Team.