2025 utility report; each result retains its measurement period
Results for Cal Water — Stockton System in San Joaquin County. Confirm the supplier and system on your bill.
See the amount, the comparison and what it means. “Below” refers to the stated benchmark, not zero risk.
38.9–150mg/L as CaCO₃
Range of source averages; groundwater range 22–290
USGS hardness classes
Surface water averages 38.9; groundwater 150. These are separate sources, not a measured household blend.
0.75mg/L
Distribution average; range ND–2.9
MRDL: 4 mg/L
Match the filter to the disinfectant used by this utility.
60µg/L (ppb)
Highest annual average; range 2.6–78
Report MCL: 80 µg/L
A system result does not measure the water at an individual home.
26µg/L (ppb)
Highest annual average; range ND–60
Report MCL: 60 µg/L
A system result does not measure the water at an individual home.
NDmg/L
Source averages; groundwater range ND–0.12
California MCL: 2 mg/L
Standard filtration and softening do not establish fluoride reduction.
NDµg/L (ppb)
90th percentile; 51 sampled sites
Report action level: 15 µg/L
No sampled sites exceeded the report’s action level. Nondetect does not mean zero or measure your home.
Continue with your home details for general filtration guidance. We will not use another utility’s numbers as your result.
Find My Water System →A city report cannot establish a well’s water quality. Well-water treatment depends on your test results and site conditions.
Explore well-water systems →The figures below are provider-specific. They are not a countywide average.
| Utility | Hardness | Hardness source |
|---|---|---|
| 38.9–150 mg/L · Soft to hard source averages | 2023–2025 |
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 | 38.9–150 mg/L as CaCO₃Range of source averages; groundwater range 22–290 | 2023–2025View source ↗ | Soft to hard source averagesSurface water averages 38.9; groundwater 150. These are separate sources, not a measured household blend. |
| Chlorine | 0.75 mg/LDistribution average; range ND–2.9 | 2025View source ↗ | Reported level below MRDLMatch the filter to the disinfectant used by this utility. |
| TTHMs | 60 µg/L (ppb)Highest annual average; range 2.6–78 | 2025View source ↗ | Reported level below benchmarkA system result does not measure the water at an individual home. |
| HAA5 | 26 µg/L (ppb)Highest annual average; range ND–60 | 2025View source ↗ | Reported level below benchmarkA system result does not measure the water at an individual home. |
| Fluoride | ND mg/LSource averages; groundwater range ND–0.12 | 2025View source ↗ | Below report benchmarkStandard filtration and softening do not establish fluoride reduction. |
| Lead | ND µg/L (ppb)90th percentile; 51 sampled sites | 2024View source ↗ | 90th percentile below action levelNo sampled sites exceeded the report’s action level. Nondetect does not mean zero or measure your home. |
| Nitrate as nitrogen | 1.7 mg/LGroundwater average; range ND–6.9; purchased-water average ND | 2025View source ↗ | Reported average below benchmarkNitrate requires treatment selected for that specific contaminant. |
| PFOS | ND–8.4 ng/L (ppt)Groundwater sample range; average ND | 2020–2025View source ↗ | Detections in some samplesAn ND average does not erase detections. Read the utility’s compliance explanation before interpreting a source maximum. |
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 ↗
Choose the system size, keep useful existing equipment, and review your filtration goals.
Source water. Local groundwater and water purchased from Stockton East Water District, sourced from New Melones and New Hogan reservoirs.
Email delivery is coming soon. Copy the report link to share it now.
More about your local water
Cal Water’s Stockton sources have different hardness: groundwater averages 150 mg/L and surface water 38.9 mg/L.
This page summarizes Cal Water’s Stockton System. Confirm the provider on your bill before using the results. Other Stockton suppliers and communities elsewhere in San Joaquin County have separate reports.
A useful local question
No. This is the Cal Water Stockton System report. Use it only after matching the supplier on your bill. A city name or ZIP code alone does not identify the water system.
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.
These local providers publish separate reports. Follow the matching utility link; the measurements above do not describe these systems.
Sources checked November 15, 2026
Your water → your home → your system
Choose the system size, keep useful existing equipment, and review your filtration goals.