Typical values from 46 sampled wells in Butte County · Full groundwater profile
What Butte County Wells Usually Need
No common nuisance problem in the typical well. The typical Butte well is moderately hard, with iron below the stain threshold and a pH of 7.4.
Safe to drink? Most sampled wells meet health limits; a yearly test confirms yours does.
Typical treatment, in plumbing order:
Usually nothing beyond routine testing. Most Butte wells need no softener or iron filter, so test before buying equipment.
Not sure what to install? Get a filter recommendation for Butte 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 Butte County
- Your county environmental health department handles private well questions in Butte 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?
Confirm with a lab test before buying equipment.
Explore California Interactive Map
Explore Butte County and nearby counties
Butte County has about 207,000 residents, and its largest communities are Chico, Oroville and Gridley. 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 Sacramento Valley – Butte.
Across 46 sampled wells, groundwater is moderately hard (6 gpg in the typical well). Arsenic, nitrate and chromium-6 were below California limits in most sampled wells, but individual wells vary, so test yours.
In this guide
Groundwater Profile: Butte County
Across 46 sampled wells, the median hardness is 6 gpg (moderately hard). At 6 gpg, Butte wells run softer than Tehama (6.7 gpg) and Yuba (8 gpg) next door. The largest California DWR Bulletin 118 groundwater basins in the county are Sacramento Valley – Butte, Sacramento Valley – Vina and Sacramento Valley – Wyandotte Creek.
Another address? Check hardness by ZIP code.
No contaminant tracked here was above its EPA guideline in the typical (median) sampled well.
Arsenic, Nitrate, Chromium-6 and Salinity in Butte County
| Contaminant | Typical well | Wells above limit | California standard |
|---|---|---|---|
| Arsenic | 0.8 µg/L | 0% of 46 | 10 µg/L (primary MCL) |
| Nitrate (as nitrogen) | 0.53 mg/L | 0% of 46 | 10 mg/L (primary MCL) |
| Chromium-6 | 0.76 µg/L | 0% of 41 | 10 µg/L (primary MCL since Oct. 1, 2024) |
| Salinity (dissolved solids) | 181 mg/L | 0% of 46 | 500 mg/L recommended, 1,000 mg/L upper (secondary) |
| Hardness | 6 gpg | 46% of 46 | No limit; above 7 gpg is hard |
Typical well = median. Standards: State Water Board; samples: Water Quality Portal, since 2000.
How Butte County Compares to California and the U.S.
See How Butte County Compares to California & the US
| Share of wells with… | Butte CountyButte | CaliforniaCA | United StatesUS |
|---|---|---|---|
| Hard water (above 7 gpg) | 46% | 64% | 60% |
| Iron above 0.3 mg/L | 9% | 9% | 19% |
| Manganese above 0.05 mg/L | 16% | 22% | 21% |
| Dissolved solids above 500 mg/L | 2% | 38% | 15% |
| Acidic water (pH below 6.5) | 16% | 2% | 14% |
| Nitrate above 10 mg/L (EPA limit) | 0% | 9% | 4% |
| Arsenic above 10 µg/L (EPA limit) | 0% | 14% | 7% |
| Chromium-6 above 10 µg/L (California limit) | 0% | 6% | — |
| Median hardness | 6 gpg | 9.9 gpg | — |
| Median pH | 7.4 | 7.6 | 7.3 |
Sources: Water Quality Portal (since 2000); US: USGS Circular 1332. Highlighted: well above the US share.
See what a typical Butte County well needs
Pre-filled with the Butte medians. Swap in your own results.
Testing Your Well in Butte County
In California, county environmental health departments handle 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 Butte County:
- Bacteria (total coliform and E. coli), nitrate and arsenic, at least once a year (California State Water Resources Control Board recommendation)
- 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
Butte County borders these counties with published reports:
Colusa County
17.4 gpg hardness · Hardness, ManganeseGlenn County
14.6 gpg hardness · HardnessPlumas County
3.2 gpg hardnessSutter County
15.2 gpg hardness · Hardness, ArsenicTehama County
6.7 gpg hardness · Chromium-6Yuba County
8 gpg hardness · HardnessCounties with similar well water
Elsewhere in California, these counties have well water like Butte County:
Frequently Asked Questions
Is well water in Butte County safe to drink?
Usually, as far as public records go: no health-based limit is commonly exceeded across 46 sampled Butte wells. Still test for bacteria and nitrate every year, because county data cannot vouch for a single well.
How hard is well water in Butte County?
Moderately hard. The median Butte well tests at 6 grains per gallon across 46 sampled wells (California median: 9.9 gpg), and 46% are above the 7 gpg mark where most homes add a softener.
Is iron a problem in Butte County well water?
Usually not. Across 45 sampled wells the median is 0 mg/L, under the 0.3 mg/L stain threshold, though 9% of wells exceed it. If your fixtures stain, test for iron and manganese before buying a filter.
Why does my well water smell like rotten eggs in Butte County?
Public lab records include sulfide results for only 6 wells in Butte, not enough to judge. The smell comes from hydrogen sulfide; a sulfide test confirms it, and at household levels it is a nuisance, not a health hazard.
Is chromium-6 a concern in Butte County well water?
Hexavalent chromium was above California’s 10 µg/L drinking water limit in 0% of 41 sampled wells in Butte 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.
Does boiling well water make it safe to drink in Butte County?
Boiling handles bacteria and nothing else. It does not soften Butte water, remove iron or take out nitrate, which ends up more concentrated. Read when boiling helps and when it hurts.
How often should I test my well water in Butte 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.
Written by Well Water Advisor Editorial Team.