Utility-reported hardness
Unavailable
Ask your provider or test your tap
Local water dashboard
Official source aggregationWater quality in Fairfield, CA 94534
Regional hardness evidence, possible serving systems, EPA compliance history, and the measurements that are—and are not—available for Solano County.
1 active health-based record(s) across possible systems
- Largest possible serving system
- City Of Fairfield
- Source water
- Surface water
- County
- Solano County
- Profile updated
Your tap water
What does the utility report?
Match the utility name to your water bill. These results describe the utility’s water, not a test at your home. A ZIP can include several water systems.
Utility hardness unavailable in this index
Nearby river or groundwater samples cannot tell us the hardness coming out of your tap. Ask your water provider for total hardness as CaCO₃, or test it at home.
Find an official utility report →At a glance
What the current records say
EPA quarter 2026Q2
All possible systems
Review needed
1 active health-based record
Measurements by utility
Each result belongs to a specific system.
Utility match
1 system
Serves 120,377 people system-wide
Match the name on your water bill
Your utility’s measurements and compliance records
These are possible serving systems. A record for one system does not apply to every home in this ZIP. Confirm your provider before interpreting a measurement or notice. Federal records can lag current utility notices.
EPA snapshot: 2026Q2. Historical window begins Jan 1, 2021.
City Of Fairfield
CA4810003 · Surface water · 120,377 people served system-wide
The system names this served city; Census place overlap links the city to this ZCTA.
1 reported active health-based record(s) for this system
Find this utility’s official report →Measurements (1)
An action level is a regulatory trigger, not a pass/fail health boundary. A reported zero is the value in the source record and does not establish that lead is absent at your tap.
Lead (90th percentile)
EPA SDWIS Lead and Copper Rule samples
- Reported level
- 0 mg/L
- Action level
- 0.015 mg/L
0% of the listed benchmark
Monitoring period: Jan 1, 2021 to Dec 31, 2023
Violation history (2)
| Rule | Status | Period |
|---|---|---|
| LEAD AND COPPER RULE REVISIONS | Unaddressed | Oct 17, 2024 |
| LEAD AND COPPER RULE REVISIONSHealth-based | Unaddressed | Oct 17, 2024 |
Hardness meter
What does nearby environmental evidence show?
320
PPM as CaCO₃
Very Hard
PPM
320
GPG
18.7
Regional environmental evidence
USGS hardness classification scale
320 PPM
Soft
0–60Moderate
61–120Hard
121–180Very hard
181+
0–60Moderate
61–120Hard
121–180Very hard
181+
Parts per million
320
mg/L as CaCO₃ equivalent
Grains per gallon
18.7
1 GPG ≈ 17.1 PPM
How to use regional evidence
These samples describe nearby environmental water. They cannot establish whether your tap water is soft or hard. Use a utility result or a tap test for appliance settings and treatment sizing.
USGS sites used
17
Nearest site
0.4 mi
Observation range
May 8, 2017–May 10, 2018
Regional evidence confidence
Low
Median of the latest source-type-aligned hardness observation at each monitoring site within 25 miles. Nearest monitoring location: SUISUN C A ROCKVILLE CA (Stream).USGS source documentation ↗Evidence tier: Regional environmental evidence. This value is not used as proof of the serving utility's treated-water hardness.
Regional context
Is 94534 typical?
These comparisons use other indexed ZIP estimates, not utility tap samples. They help show local context without replacing a household test.
Fairfield median
298 PPM
22 PPM higher3 indexed ZIP readings · Range 251.5–320 PPM
California median
254 PPM
66 PPM higher549 indexed ZIP readings · Range 42.6–1531.5 PPM
Evidence-first next steps
Confirm the problem before choosing treatment
This profile can help you ask the right question. It cannot select equipment for a property without a current result from the serving utility or the tap.
Confirm the serving system
ZIP boundaries and utility service areas do not perfectly match. Verify the system on a water bill before relying on system-wide records.
Read the current utility report
An active health-based record is present. Follow the utility's current notice and public-health instructions.
Find an official utility report →Test for the decision you face
Use a tap hardness test before sizing a softener. For health concerns, use a certified laboratory and the correct sampling protocol.
Convert your hardness test result →Nearby indexed reports
More local profiles in Fairfield
Estimates can differ across a city because monitoring locations and associated systems differ.
Frequently asked
Water questions for Fairfield
Is tap water safe in Fairfield?+
EPA ECHO reports 1 active health-based violation among the associated community water systems. Review the affected utility's current notice and Consumer Confidence Report.
How hard is the water?+
Utility-reported hardness is unavailable in this index. Regional samples do not establish tap-water hardness. Ask your provider or test your tap.
Do I need a water softener?+
Confirm hardness at your tap and consider actual scale or spotting before choosing treatment. Regional environmental values cannot determine whether you need a softener. A softener addresses hardness, not every contaminant.