Hardness
Moderately hard74mg/L as CaCO₃
average at both treatment plants
USGS hardness classes
About 4.3 gpg. Plant ranges span 54–96 mg/L, from soft to moderately hard.
2025
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Your local water, explained
Contra Costa County Water Quality Report
Compare CCWD and EBMUD without mixing their results.
CCWD reports a 74 mg/L hardness average at both treatment plants; EBMUD reports plant ranges spanning 14–160 mg/L. Select the provider on your bill to see the relevant results. These are separate utility reports, not a blended Contra Costa County average.
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Your water
Match the name on your water bill.
Check the supplier on your water bill. City and county boundaries can include several water systems.
Only the listed water system is summarized here. Choose “Other / not sure” if your bill shows a different supplier.
Confirm the provider on your bill, or choose “Other / not sure” to continue without a matched report.
These are utility measurements, not a test at your tap or a current service advisory. Sources checked October 27, 2026
Choose the right utility report
The figures below are provider-specific. They are not a countywide average.
| Utility | Hardness | Hardness source |
|---|---|---|
| 74 mg/L as CaCO₃ · Moderately hard | 2025 · average at both treatment plants | |
| 14–160 mg/L as CaCO₃ · Soft to hard, depending on supply | 2025 · range across treatment plants |
Showing utility report
Contra Costa Water District (CCWD)
2025 utility report; measurement years are shown with each result
Use these results only if Contra Costa Water District (CCWD) supplies your home. County and ZIP boundaries do not confirm a water provider.
Your water at a glance
See the amount, the comparison and what it means. “Below” refers to the stated benchmark, not zero risk.
Chloramine
Below the 4 mg/L limit2.1mg/L as chlorine
system average; range ND–3.4
MRDL: 4 mg/L
Choose a filter with a verified chloramine reduction claim at the required flow.
2025
View source ↗TTHMs
Reported value below 80 ppb28µg/L (ppb)
system average; range 13–33
MCL: 80 ppb
The report’s compliance method and a home’s individual sample are different measures.
2025
View source ↗HAA5
Reported value below 60 ppb16µg/L (ppb)
system average; range 4.4–21
MCL: 60 ppb
Haloacetic acids are disinfection byproducts.
2025
View source ↗Fluoride
Below California’s 2 mg/L limit0.7mg/L
system average; range 0.6–0.9
California MCL: 2 mg/L
Fluoride reduction needs an appropriate dedicated treatment stage.
2025
View source ↗Lead
Below action level; one high sampleND90th percentile
64 sampled homes
Report action level: 15 ppb
One of 64 homes exceeded 15 ppb. The system percentile is not a guarantee for an individual tap.
June 2025
View source ↗Arsenic
Unknown, not zeroNot listedin the selected report tables
no numeric result shown
No comparison available
Ask the utility for the relevant monitoring result if arsenic is a specific concern.
2025 report
View source ↗PFAS
Non-detect does not mean zeroNot detectedutility’s drinking-water statement
no compound-level values shown here
No numeric comparison
CCWD reports no detection in its drinking water. Check its detailed PFAS results for compounds and reporting limits.
2025 report
View source ↗View Full Water ReportOpen the measured results, dates, comparisons and original utility report.
The numbers behind your report
Selected results with the original sampling dates and measurement basis. Open the utility report for every parameter, notice and footnote.
Open the complete utility report ↗
| What was measured | Reported amount | Sample year / source date | How to read it |
|---|---|---|---|
| Hardness | 74 mg/L as CaCO₃average at both treatment plants | 2025View source ↗ | Moderately hardAbout 4.3 gpg. Plant ranges span 54–96 mg/L, from soft to moderately hard. |
| Chloramine | 2.1 mg/L as chlorinesystem average; range ND–3.4 | 2025View source ↗ | Below the 4 mg/L limitChoose a filter with a verified chloramine reduction claim at the required flow. |
| TTHMs | 28 µg/L (ppb)system average; range 13–33 | 2025View source ↗ | Reported value below 80 ppbThe report’s compliance method and a home’s individual sample are different measures. |
| HAA5 | 16 µg/L (ppb)system average; range 4.4–21 | 2025View source ↗ | Reported value below 60 ppbHaloacetic acids are disinfection byproducts. |
| Fluoride | 0.7 mg/Lsystem average; range 0.6–0.9 | 2025View source ↗ | Below California’s 2 mg/L limitFluoride reduction needs an appropriate dedicated treatment stage. |
| Lead | ND 90th percentile64 sampled homes | June 2025View source ↗ | Below action level; one high sampleOne of 64 homes exceeded 15 ppb. The system percentile is not a guarantee for an individual tap. |
| Arsenic | Not listed in the selected report tablesno numeric result shown | 2025 reportView source ↗ | Unknown, not zeroAsk the utility for the relevant monitoring result if arsenic is a specific concern. |
| PFAS | Not detected utility’s drinking-water statementno compound-level values shown here | 2025 reportView source ↗ | Non-detect does not mean zeroCCWD reports no detection in its drinking water. Check its detailed PFAS results for compounds and reporting limits. |
| Hardness — Bollman plant | 74 mg/L as CaCO₃average; range 59–90 | 2025View source ↗ | Moderately hard averageBollman is the district’s Concord treatment plant. |
| Hardness — Randall-Bold plant | 74 mg/L as CaCO₃average; range 54–96 | 2025View source ↗ | Moderately hard averageThe plant’s range crosses the soft/moderately hard boundary. |
| Copper | 0.11 mg/L90th percentile | June 2025View source ↗ | Below the 1.3 mg/L action levelNone of 64 homes exceeded the action level. |
| TDS — Bollman / Randall-Bold | 212 / 199 mg/Lplant averages | 2025View source ↗ | Below the 500 mg/L secondary limitFull sample ranges were 159–281 and 137–301 mg/L. |
| Chloride — Bollman / Randall-Bold | 45 / 46 mg/Lplant averages | 2025View source ↗ | Below the 250 mg/L secondary limitThis is chloride, not the disinfectant chlorine. |
| Sulfate — Bollman / Randall-Bold | 58 / 48 mg/Lplant averages | 2025View source ↗ | Below the 250 mg/L secondary limitSulfate and sulfur odors are not interchangeable measurements. |
| Sodium — Bollman / Randall-Bold | 47 / 43 mg/Lplant averages | 2025View source ↗ | No MCL listed in this tableA softener does not remove sodium. |
In drinking water, ppm ≈ mg/L, ppb ≈ µg/L and ppt ≈ ng/L. Calculated hardness in grains per US gallon (gpg) = mg/L as CaCO₃ ÷ 17.118, rounded to one decimal. ND means below the reporting limit, not zero.
MCL is an enforceable contaminant limit; MRDL is a disinfectant limit. A PHG is a health goal, not the legal limit. Lead/copper action levels use system sampling percentiles, not a safe-tap threshold. TTHM/HAA5 comparisons use locational running annual averages.
PFAS results are compound-specific. Source monitoring, entry-point samples and tap tests are different. Notification and response levels in a utility report are not maximum contaminant levels; do not infer a compliance violation from a single value. EPA PFAS benchmarks and implementation ↗
Turn your report into a plan for your home.
Choose the system size, keep useful existing equipment, and review your filtration goals.
Source water. Sacramento–San Joaquin Delta water, with Los Vaqueros Reservoir storage and blending, treated at the Bollman and Randall-Bold plants.
Showing utility report
East Bay Municipal Utility District (EBMUD)
2025 utility report; measurement years are shown with each result
Use these results only if East Bay Municipal Utility District (EBMUD) supplies your home. County and ZIP boundaries do not confirm a water provider.
Your water at a glance
See the amount, the comparison and what it means. “Below” refers to the stated benchmark, not zero risk.
Hardness
Soft to hard, depending on supply14–160mg/L as CaCO₃
range across treatment plants
USGS hardness classes
Walnut Creek, Lafayette and Orinda ranges are soft; Sobrante is moderately hard; Upper San Leandro is hard.
2025
View source ↗Chloramine
Below the 4 mg/L limit2.4mg/L as chlorine
highest running annual average
MRDL: 4 mg/L
Individual samples ranged 0.07–3.71 mg/L. Select treatment with a verified chloramine claim.
2025
View source ↗TTHMs
Below the 80 ppb limit57µg/L (ppb)
highest locational annual average
MCL: 80 ppb
Some individual samples reached 110 ppb. The compliance comparison uses locational running annual averages.
2025
View source ↗HAA5
Below the 60 ppb limit50µg/L (ppb)
highest locational annual average
MCL: 60 ppb
Individual samples reached 76 ppb. An individual sample and an annual average are different measures.
2025
View source ↗Fluoride
Below California’s 2 mg/L limit0.7mg/L
system average; samples 0.6–0.8
California MCL: 2 mg/L
Fluoride requires dedicated treatment if reducing it is a goal.
2025
View source ↗Lead
Below the report’s action levelND90th percentile
53 sampled homes
Report action level: 15 ppb
No samples exceeded 15 ppb; reported range ND–13.3 ppb. Home plumbing can change tap results.
2024
View source ↗Arsenic
Unknown, not zeroNot listedin the selected report tables
no numeric result shown
No comparison available
The absence of a value in these detected-contaminant tables does not establish your home’s arsenic level.
2025 report
View source ↗PFAS
Compound-specific findingsDetectedselected individual samples
PFHxA and PFBA in UCMR5 table
No single PFAS total
Selected plant samples contained PFHxA or PFBA even though the table’s system averages were ND. See the full report for context.
2025 report
View source ↗View Full Water ReportOpen the measured results, dates, comparisons and original utility report.
The numbers behind your report
Selected results with the original sampling dates and measurement basis. Open the utility report for every parameter, notice and footnote.
Open the complete utility report ↗
| What was measured | Reported amount | Sample year / source date | How to read it |
|---|---|---|---|
| Hardness | 14–160 mg/L as CaCO₃range across treatment plants | 2025View source ↗ | Soft to hard, depending on supplyWalnut Creek, Lafayette and Orinda ranges are soft; Sobrante is moderately hard; Upper San Leandro is hard. |
| Chloramine | 2.4 mg/L as chlorinehighest running annual average | 2025View source ↗ | Below the 4 mg/L limitIndividual samples ranged 0.07–3.71 mg/L. Select treatment with a verified chloramine claim. |
| TTHMs | 57 µg/L (ppb)highest locational annual average | 2025View source ↗ | Below the 80 ppb limitSome individual samples reached 110 ppb. The compliance comparison uses locational running annual averages. |
| HAA5 | 50 µg/L (ppb)highest locational annual average | 2025View source ↗ | Below the 60 ppb limitIndividual samples reached 76 ppb. An individual sample and an annual average are different measures. |
| Fluoride | 0.7 mg/Lsystem average; samples 0.6–0.8 | 2025View source ↗ | Below California’s 2 mg/L limitFluoride requires dedicated treatment if reducing it is a goal. |
| Lead | ND 90th percentile53 sampled homes | 2024View source ↗ | Below the report’s action levelNo samples exceeded 15 ppb; reported range ND–13.3 ppb. Home plumbing can change tap results. |
| Arsenic | Not listed in the selected report tablesno numeric result shown | 2025 reportView source ↗ | Unknown, not zeroThe absence of a value in these detected-contaminant tables does not establish your home’s arsenic level. |
| PFAS | Detected selected individual samplesPFHxA and PFBA in UCMR5 table | 2025 reportView source ↗ | Compound-specific findingsSelected plant samples contained PFHxA or PFBA even though the table’s system averages were ND. See the full report for context. |
| Hardness — Walnut Creek | 15–21 mg/L as CaCO₃plant sample range | 2025View source ↗ | SoftPlant-associated samples may include water from another plant; confirm your current blend. |
| Hardness — Lafayette | 14–27 mg/L as CaCO₃plant sample range | 2025View source ↗ | SoftPlant-associated samples may include water from another plant; confirm your current blend. |
| Hardness — Orinda | 14–40 mg/L as CaCO₃plant sample range | 2025View source ↗ | SoftPlant-associated samples may include water from another plant; confirm your current blend. |
| Hardness — Sobrante | 64–98 mg/L as CaCO₃plant sample range | 2025View source ↗ | Moderately hardPlant-associated samples may include water from another plant; confirm your current blend. |
| Hardness — Upper San Leandro | 140–160 mg/L as CaCO₃plant sample range | 2025View source ↗ | HardPlant-associated samples may include water from another plant; confirm your current blend. |
| PFHxA — Upper San Leandro | ND–3.4 ng/L (ppt)individual sample range | 2025 reportView source ↗ | Below report’s 1,000 ppt notification levelUCMR5 result; the notification level is not an MCL. |
| PFBA — Upper San Leandro | ND–5.2 ng/L (ppt)individual sample range | 2025 reportView source ↗ | No benchmark listed in this tableSobrante range was ND–5.1 ppt; other listed plants were ND. |
| Chlorate | 108 µg/L (ppb)system average | 2025View source ↗ | Below report’s 800 ppb notification levelA notification level is not an enforceable MCL. |
| NDMA | 3.9 ng/L (ppt)highest locational annual average | 2025View source ↗ | Below report’s 10 ppt notification levelHighest individual sample in the table was 6.5 ppt. |
| Total dissolved solids | 65 mg/Lsystem average | 2025View source ↗ | Below the 500 mg/L secondary limitTDS describes dissolved material collectively; it is not a contaminant-specific test. |
In drinking water, ppm ≈ mg/L, ppb ≈ µg/L and ppt ≈ ng/L. Calculated hardness in grains per US gallon (gpg) = mg/L as CaCO₃ ÷ 17.118, rounded to one decimal. ND means below the reporting limit, not zero.
MCL is an enforceable contaminant limit; MRDL is a disinfectant limit. A PHG is a health goal, not the legal limit. Lead/copper action levels use system sampling percentiles, not a safe-tap threshold. TTHM/HAA5 comparisons use locational running annual averages.
PFAS results are compound-specific. Source monitoring, entry-point samples and tap tests are different. Notification and response levels in a utility report are not maximum contaminant levels; do not infer a compliance violation from a single value. EPA PFAS benchmarks and implementation ↗
Turn your report into a plan for your home.
Choose the system size, keep useful existing equipment, and review your filtration goals.
Source water. Sierra Nevada water from the Mokelumne River and water from East Bay reservoirs. Plant supplies and seasonal blends affect hardness.
Your provider needs its own report.
Continue with your home details for general filtration guidance. We will not use another utility’s numbers as your result.
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What this means for your home
Contra Costa County includes CCWD treated-water customers, EBMUD customers and other water systems. The provider selector keeps their results separate. Even the city name alone may not identify a retailer or treatment plant. If neither listed provider matches the bill, use the other-provider route and the appropriate official report before choosing treatment.
Related city reports
Different name on your water bill?
These local providers publish separate reports. Follow the matching utility link; the measurements above do not describe these systems.
A useful local question
Why do Contra Costa County hardness reports show different numbers?
Different utilities and plants use different sources and blends. CCWD’s reported average is moderately hard; EBMUD’s plant ranges run from soft to hard. Both require source-specific interpretation. Select the utility first, then confirm home hardness if considering a softener for scale.
Sources and methodology
We keep each utility’s results separate, show the reported sample year, and distinguish averages, maxima and tap-sampling percentiles. Hardness classifications use USGS ranges. Missing data stays unknown.
- Contra Costa Water District (CCWD) ↗2025 utility report; measurement years are shown with each result
- Contra Costa Water District annual reports ↗
- East Bay Municipal Utility District (EBMUD) ↗2025 utility report; measurement years are shown with each result
- EBMUD water quality and original annual reports ↗
- USGS hardness classification
- EPA PFAS benchmarks and implementation
Sources checked October 27, 2026
Your water → your home → your system
Turn your report into a plan for your home.
Choose the system size, keep useful existing equipment, and review your filtration goals.
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