Typical values from 8 sampled wells in Solano County · Full groundwater profile
Solano County Well Water at a Glance
No common nuisance problem in the typical well. The typical Solano well is very hard, with iron below the stain threshold and a pH of 7.6.
Drink it untreated? Generally yes in the records, though only your own test covers your well.
What a typical home here installs:
Usually nothing beyond routine testing. Most Solano wells need no softener or iron filter, so test before buying equipment.
Not sure what to install? Get a filter recommendation for Solano County homesOn city or county water instead? Your utility publishes an annual water quality report; this page covers private wells. Find your utility's report
On this page (8 sections)
Where to Test Well Water in Solano County
- Your county environmental health department handles private well questions in Solano 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 Solano County and nearby counties
Solano County has about 449,000 residents, and its largest communities are Vallejo, Fairfield and Vacaville. 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 – Solano.
Across 8 sampled wells, groundwater is very hard (13.9 gpg in the typical well). Arsenic turned up above the 10 µg/L limit in a small sample of wells. These have no taste or smell, so only a lab test shows whether your own well is affected.
In this guide
Groundwater Profile: Solano County
The largest California DWR Bulletin 118 groundwater basins in the county are Sacramento Valley – Solano, Suisun-Fairfield Valley and Napa-Sonoma Valley – Napa-Sonoma Lowlands.
Another address? Check hardness by ZIP code.
What shows up in local well samples:
- HardnessLimited local data (fewer than 20 samples): individual well testing recommended.
Calcium and magnesium dissolved from limestone. Leaves scale on fixtures and water heaters and reduces soap lather. Not a health risk.
Water softener sizing - Total dissolved solidsMedian 582 mg/L; 63% of sampled wells above 500 mg/L
A high overall mineral load that affects taste and causes scaling. The EPA aesthetic guideline is 500 mg/L.
Reverse osmosis guide - ArsenicFound above the drinking water limit locally. Limited local data (fewer than 20 samples): individual well testing recommended.
Odorless and tasteless, with an EPA limit of 10 µg/L. Only a lab test detects it.
How to test your well
Arsenic, Nitrate, Chromium-6 and Salinity in Solano County
| Contaminant | Typical well | Wells above limit | California standard |
|---|---|---|---|
| Arsenic | 2.2 µg/L | Limited data (8 wells) | 10 µg/L (primary MCL) |
| Nitrate (as nitrogen) | 1.18 mg/L | Limited data (8 wells) | 10 mg/L (primary MCL) |
| Chromium-6 | 7.14 µg/L | Limited data (3 wells) | 10 µg/L (primary MCL since Oct. 1, 2024) |
| Salinity (dissolved solids) | 582 mg/L | Limited data (8 wells) | 500 mg/L recommended, 1,000 mg/L upper (secondary) |
| Hardness | 13.9 gpg | Limited data (8 wells) | No limit; above 7 gpg is hard |
Typical well = median. Standards: State Water Board; samples: Water Quality Portal, since 2000.
How Solano County Compares to California and the U.S.
See How Solano County Compares to California & the US
| Share of wells with… | Solano CountySolano | CaliforniaCA | United StatesUS |
|---|---|---|---|
| Hard water (above 7 gpg) | Limited data | 64% | 60% |
| Iron above 0.3 mg/L | Limited data | 9% | 19% |
| Manganese above 0.05 mg/L | Limited data | 22% | 21% |
| Dissolved solids above 500 mg/L | 63% | 38% | 15% |
| Acidic water (pH below 6.5) | 0% | 2% | 14% |
| Nitrate above 10 mg/L (EPA limit) | Limited data | 9% | 4% |
| Arsenic above 10 µg/L (EPA limit) | Limited data | 14% | 7% |
| Chromium-6 above 10 µg/L (California limit) | Limited data | 6% | — |
| Median hardness | 13.9 gpg | 9.9 gpg | — |
| Median pH | 7.6 | 7.6 | 7.3 |
Sources: Water Quality Portal (since 2000); US: USGS Circular 1332. Highlighted: well above the US share.
See what a typical Solano County well needs
Pre-filled with the Solano medians. Swap in your own results.
Testing Your Well in Solano 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 Solano 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
- Total dissolved solids (salinity), compared with California’s 500 mg/L recommended and 1,000 mg/L upper limits
- 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
Solano County borders these counties with published reports:
Contra Costa County
Napa County
5.2 gpg hardness · Manganese, ArsenicSacramento County
6.8 gpg hardness · Arsenic, Chromium-6Sonoma County
7.3 gpg hardness · HardnessYolo County
14.6 gpg hardness · HardnessCounties with similar well water
Farther away, these California counties share the same main water issues:
Frequently Asked Questions
Is well water in Solano County safe to drink?
Usually, as far as public records go: no health-based limit is commonly exceeded across 8 sampled Solano wells. Still test for bacteria and nitrate every year, because county data cannot vouch for a single well.
How hard is well water in Solano County?
Groundwater samples from 8 wells in Solano County have a median hardness of 13.9 grains per gallon (238 mg/L), which the USGS classes as very hard. Limited local data (fewer than 20 samples): individual well testing recommended. The California statewide median is 9.9 gpg.
Is iron a problem in Solano County well water?
The median iron level across 8 sampled wells is 0 mg/L, below the EPA aesthetic guideline of 0.3 mg/L (limited local data (fewer than 20 samples): individual well testing recommended). Most wells will not stain, but if yours does, a lab test tells you whether iron or manganese is the cause.
Why does my well water smell like rotten eggs in Solano County?
Public lab records include sulfide results for only 1 wells in Solano, 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 Solano County well water?
Only 3 wells in Solano County have been sampled for hexavalent chromium, too few to say how common it is. California’s limit is 10 µg/L, and only a lab test of your own well can show whether it is affected.
Can I install a salt-based water softener in Solano 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 Solano County?
Only against germs. A one-minute rolling boil kills bacteria after a positive test or a boil water notice, but it leaves minerals and chemicals behind in less water. See what boiling can and cannot fix.
How often should I test my well water in Solano 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.