2026 water quality report · 2025 reporting year
Public water system GA0670003. Use these measurements only for this system; they do not describe private wells or every address in Cobb County.
See the amount, the comparison and what it means. “Below” refers to the stated benchmark, not zero risk.
31.7 / 35.1mg/L
Quarles average: 31.7 mg/L; Wyckoff average: 35.1 mg/L. These wholesale plant averages are about 1.9 and 2.1 gpg.
USGS: soft ≤60; moderately hard 61–120 mg/L as CaCO₃.
2.00mg/L
Reported residual; range 0.00–2.00.
MRDL in the utility report: 4 mg/L.
0.95mg/L
Highest result; range 0.54–0.95.
MCL in the utility report: 4 mg/L.
60µg/L
Highest locational running annual average, site 513; samples 11.92–80.9.
MCL in the utility report: 80 µg/L.
37µg/L
Highest locational running annual average, site 504; samples 8.57–47.1.
MCL in the utility report: 60 µg/L.
0.79mg/L
Highest result; measured together as nitrogen, range 0.26–0.79.
MCL in the utility report: 10 mg/L.
2.9µg/L
90th percentile; two samples over the action level, range 0–37.
AL in the utility report: 15 µg/L.
0.12NTU
Plant-level result at the supplier’s treatment plants.
100% of samples were below 0.3 NTU in the report.
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 |
|---|---|---|
| 31.7 / 35.1 mg/L · Soft at both plants | 2025 · wholesaler plant averages |
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 | 31.7 / 35.1 mg/LQuarles average: 31.7 mg/L; Wyckoff average: 35.1 mg/L. These wholesale plant averages are about 1.9 and 2.1 gpg. | 2025 · wholesaler plant averagesView source ↗ | Soft at both plants |
| Free chlorine | 2.00 mg/LReported residual; range 0.00–2.00. | 2025View source ↗ | Below 4 mg/L disinfectant limitMRDL in the utility report: 4 mg/L. |
| Fluoride | 0.95 mg/LHighest result; range 0.54–0.95. | 2025View source ↗ | Below 4 mg/L limitMCL in the utility report: 4 mg/L. |
| Total trihalomethanes (TTHM) | 60 µg/LHighest locational running annual average, site 513; samples 11.92–80.9. | 2025View source ↗ | Below 80 µg/L limitMCL in the utility report: 80 µg/L. |
| Haloacetic acids (HAA5) | 37 µg/LHighest locational running annual average, site 504; samples 8.57–47.1. | 2025View source ↗ | Below 60 µg/L limitMCL in the utility report: 60 µg/L. |
| Nitrate/nitrite | 0.79 mg/LHighest result; measured together as nitrogen, range 0.26–0.79. | 2025View source ↗ | Below 10 mg/L limitMCL in the utility report: 10 mg/L. |
| Lead | 2.9 µg/L90th percentile; two samples over the action level, range 0–37. | 2025View source ↗ | Below 15 µg/L action levelAL in the utility report: 15 µg/L. |
| Turbidity | 0.12 NTUPlant-level result at the supplier’s treatment plants. | 2025View source ↗ | Treatment target met100% of samples were below 0.3 NTU in the report. |
| Copper | 0.078 mg/L90th percentile; range 0.0038–0.47; no samples exceeded the action level. | 2025View source ↗ | Below 1.3 mg/L action levelAL in the utility report: 1.3 mg/L. |
| Chlorite | 0.24 mg/LReported result; range 0.013–0.24. | 2025View source ↗ | Below 1 mg/L limitMCL in the utility report: 1 mg/L. |
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 means a regulatory contaminant limit; MRDL is a disinfectant limit. Lead and copper use tap-sampling action levels. TTHM and HAA5 compliance is assessed using running averages at specific locations, not the highest single sample.
PFAS results depend on the compound, sample location, year and reporting limit. A missing result or nondetect is not proof of zero PFAS. EPA PFAS benchmarks and implementation ↗
Choose the system size, keep useful existing equipment, and review your filtration goals.
Source water. Cobb buys treated water from the Cobb County–Marietta Water Authority. Its Quarles and Wyckoff plants serve different source supplies; distribution samples in the county report are separately identified.
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More about your local water
Two supply plants reported soft water.
The county purchases treated water. A supplier plant average can guide a scale decision, but it cannot establish hardness in a particular house or the lead concentration at its faucet.
A useful local question
Cobb’s sample range reached 80.9 µg/L. The 80 µg/L limit is assessed using a rolling average at each location; the county reports 60 µg/L as the highest of those averages.
Results retain the utility, sample year, units and comparison used in the source. Hardness is shown separately as a utility measurement, utility guidance or regional estimate. USGS categories describe mineral content, not drinking-water safety.
Use the published report for your own retail water system. These sources can help identify the right report; a county or ZIP alone cannot confirm service.
Sources reviewed November 5, 2026.
Your water → your home → your system
Choose the system size, keep useful existing equipment, and review your filtration goals.