Hardness
Moderately hard / hard109.8 / 138mg/L as CaCO₃
Sonoma Water / Santa Rosa reporting values
USGS hardness classes
Purchased-water range 106–125; local-well range 136–140. Do not average the two columns.
2025View source
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- 2Your home
- 3Your system
Sonoma County Water Quality Report
Showing utility report
City of Santa Rosa Water
2025 utility report; each result retains its measurement period
Results for City of Santa Rosa Water in Sonoma County. Confirm the supplier and system on your bill.
Your water at a glance
See the amount, the comparison and what it means. “Below” refers to the stated benchmark, not zero risk.
Chlorine
Reported level below MRDL1.16mg/L
Santa Rosa reporting value; range 0.11–1.90
MRDL: 4 mg/L
Match the filter to the disinfectant used by this utility.
2025View source
TTHMs
Reported level below benchmark25.5µg/L (ppb)
Santa Rosa reporting value; range 18.7–36.0
Report MCL: 80 µg/L
A system result does not measure the water at an individual home.
2025View source
HAA5
Reported level below benchmark8.4µg/L (ppb)
Santa Rosa reporting value; range 4.8–12.4
Report MCL: 60 µg/L
A system result does not measure the water at an individual home.
2025View source
Fluoride
Below report benchmark0.17mg/L
Local-well reporting value; range 0.16–0.18
California MCL: 2 mg/L
Purchased Sonoma Water is reported below 0.1 mg/L. Keep the source columns separate.
2025View source
Lead
90th percentile below action level1.34µg/L (ppb)
Santa Rosa 90th percentile; reported range ND–18.2
Report action level: 15 µg/L
Individual samples differ from the percentile. Use a household test for a concern about your own plumbing.
2025View source
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The figures below are provider-specific. They are not a countywide average.
| Utility | Hardness | Hardness source |
|---|---|---|
| 109.8 / 138 mg/L · Moderately hard / hard | 2025 |
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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.
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| What was measured | Reported amount | Sample year / source date | How to read it |
|---|---|---|---|
| Hardness | 109.8 / 138 mg/L as CaCO₃Sonoma Water / Santa Rosa reporting values | 2025View source ↗ | Moderately hard / hardPurchased-water range 106–125; local-well range 136–140. Do not average the two columns. |
| Chlorine | 1.16 mg/LSanta Rosa reporting value; range 0.11–1.90 | 2025View source ↗ | Reported level below MRDLMatch the filter to the disinfectant used by this utility. |
| TTHMs | 25.5 µg/L (ppb)Santa Rosa reporting value; range 18.7–36.0 | 2025View source ↗ | Reported level below benchmarkA system result does not measure the water at an individual home. |
| HAA5 | 8.4 µg/L (ppb)Santa Rosa reporting value; range 4.8–12.4 | 2025View source ↗ | Reported level below benchmarkA system result does not measure the water at an individual home. |
| Fluoride | 0.17 mg/LLocal-well reporting value; range 0.16–0.18 | 2025View source ↗ | Below report benchmarkPurchased Sonoma Water is reported below 0.1 mg/L. Keep the source columns separate. |
| Lead | 1.34 µg/L (ppb)Santa Rosa 90th percentile; reported range ND–18.2 | 2025View source ↗ | 90th percentile below action levelIndividual samples differ from the percentile. Use a household test for a concern about your own plumbing. |
| Nitrate as nitrogen | <0.2 mg/LSanta Rosa result; purchased Sonoma Water below 0.4 | 2025View source ↗ | Reported average below benchmarkNitrate requires treatment selected for that specific contaminant. |
| Total dissolved solids | 156.6 / 350 mg/LSonoma Water / Santa Rosa reporting values | 2025View source ↗ | Below report secondary benchmarkThese are separate source values. Dissolved solids and hardness are different measurements. |
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 ↗
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Source water. Russian River supply purchased through Sonoma Water and Santa Rosa’s own groundwater wells.
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What this means for your home
The report separates Sonoma Water’s 109.8 mg/L hardness value from Santa Rosa’s 138 mg/L local-well value.
Use Santa Rosa’s distribution results for a Santa Rosa Water account. The paired source columns are kept separate here. A Sonoma County address served by another retailer or private well needs a different report or test.
A useful local question
Why are there two hardness values in Santa Rosa’s report?
The report has separate columns for purchased Sonoma Water and Santa Rosa’s local supply. The values describe those sources, not a calculated county average or a guaranteed blend at your home.
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.
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.
- City of Santa Rosa Water ↗2025 utility report; each result retains its measurement period
- USGS hardness classification
- EPA PFAS benchmarks and implementation
Sources checked November 15, 2026
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