Hardness
Very hard, historical result269 mg/L as CaCO₃
Average; range 236–302; 2025 report has no replacement figure
USGS very hard: >180 mg/L
2024
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- 2Your home
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Your local water, explained
San Marcos Water Quality Report
Very hard water and a reported 2025 byproduct violation.
San Marcos' available hardness figure is a very hard 269 mg/L average from 2024. Its 2025 report and official notice also document a TTHM annual-average violation. The dates and measurement basis matter when interpreting both.
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Utility data is a starting point. It is not a test of your tap or a live advisory. Sources checked October 23, 2026
Showing utility report
City of San Marcos
2025 report; each row keeps its measurement year
Results for City of San Marcos customers on system TX1050001. Other districts and private wells need their own reports.
Your water at a glance
See the amount, the comparison and what it means. “Below” refers to the stated benchmark, not zero risk.
Free chlorine
Below stated benchmark1.26 ppm
Average; range 0.30–2.42
MRDL 4 ppm
2025
View source ↗TTHMs
Above limit in 202581 ppb
Highest LRAA; individual range 1.1–94.3 ppb
MCL 80 ppb, LRAA basis
Official notice confirms0.081 mg/L=81 ppb. CCR unit/No-violation cells conflict with its own violation section; use the official notice for this interpretation.
2025; Q4 violation
View source ↗HAA5
Below limit25 ppb
Highest LRAA; City of Kyle report's purchased-water San Marcos table confirms units and value
MCL 60 ppb, LRAA basis
San Marcos CCR prints ppm in HAA5 cell; corroborating official supplier-results table usesppb.
2025
View source ↗Fluoride
Below limit0.21 ppm
Highest result; range 0.16–0.21
MCL 4 ppm
January 7, 2025
View source ↗Lead
Below action level1.63 ppb
90th percentile; range 0–2.22; zero sites over AL
Report action level 15 ppb; MCLG0
2022–2024 monitoring period
View source ↗PFAS
Cannot assess high or lowNot verified
No compound-specific result assessed in this summary
This does not establish whether PFAS are present or absent. Check compound-specific testing before choosing treatment.
2025 report review
View source ↗Nitrate
Below limit1.77 ppm
Highest result; range 1.16–1.77
MCL 10 ppm
January 7, 2025
View source ↗View Full Water ReportOpen the measured results, dates, comparisons and original utility report.
The numbers behind your report
Selected useful results—not a replacement for the utility’s complete report. Older measurements retain their original year.
Open the complete utility report ↗
| What was measured | Reported amount | Sample year / source date | How to read it |
|---|---|---|---|
| Hardness | 269 mg/L as CaCO₃ Average; range 236–302; 2025 report has no replacement figure | 2024View source ↗ | Very hard, historical result · USGS very hard: >180 mg/L |
| Free chlorine | 1.26 ppm Average; range 0.30–2.42 | 2025View source ↗ | Below stated benchmark · MRDL 4 ppm |
| Total trihalomethanes (TTHM) | 81 ppb Highest LRAA; individual range 1.1–94.3 ppb | 2025; Q4 violationView source ↗ | Above limit in 2025 · MCL 80 ppb, LRAA basisOfficial notice confirms0.081 mg/L=81 ppb. CCR unit/No-violation cells conflict with its own violation section; use the official notice for this interpretation. |
| Haloacetic acids (HAA5) | 25 ppb Highest LRAA; City of Kyle report's purchased-water San Marcos table confirms units and value | 2025View source ↗ | Below limit · MCL 60 ppb, LRAA basisSan Marcos CCR prints ppm in HAA5 cell; corroborating official supplier-results table usesppb. |
| Fluoride | 0.21 ppm Highest result; range 0.16–0.21 | January 7, 2025View source ↗ | Below limit · MCL 4 ppm |
| Nitrate | 1.77 ppm Highest result; range 1.16–1.77 | January 7, 2025View source ↗ | Below limit · MCL 10 ppm |
| Lead | 1.63 ppb 90th percentile; range 0–2.22; zero sites over AL | 2022–2024 monitoring periodView source ↗ | Below action level · Report action level 15 ppb; MCLG0A system sampling percentile is not a measurement of your faucet. |
| Copper | 0.171 ppm 90th percentile; range 0.0133–0.31; zero sites over AL | 2022–2024 monitoring periodView source ↗ | Below action level · Action level 1.3 ppmA system sampling percentile is not a measurement of your faucet. |
| PFAS | Not verified No compound-specific result assessed in this summary | 2025 report reviewView source ↗ | Cannot assess high or lowThis does not establish whether PFAS are present or absent. Check compound-specific testing before choosing treatment. |
ppm ≈ mg/L; ppb ≈ µg/L; ppt ≈ ng/L in drinking water. Hardness in gpg = mg/L as CaCO₃ ÷ 17.1. ND means not detected at the method’s reporting limit—not zero.
MCL is a maximum contaminant level. MRDL is a disinfectant limit. Lead/copper action levels use system sampling percentiles and are not a safe-tap threshold. TTHM/HAA5 compliance uses locational annual averages.
PFOA/PFOS comparisons use EPA’s 4 ppt values. Historical detections are not a present compliance finding; EPA assesses compliance using running annual averages. Rule implementation is being reviewed. EPA PFAS benchmarks and implementation ↗
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Source water. Edwards Aquifer groundwater, Carrizo-Wilcox Aquifer water via Alliance Regional Water Authority1B, and Canyon Lake surface water pumped from Lake Dunlap.
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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More about your local water
What this means for your home
This page covers City of San Marcos PWS TX1050001, not the separate Texas State University, Kingswood or Oakridge systems. The 2025 report does not replace the older hardness measurement. Follow the utility for current notices; this summary is not a live advisory.
A useful local question
Why does this page use an older hardness result?
The 2025 report does not publish a replacement hardness figure. The 2024 average of 269 mg/L remains useful, clearly dated evidence for softening, while a current home test confirms the final setting.
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.
- City of San Marcos ↗2025 report; each row keeps its measurement year
- Official utility notice ↗
- City of San Marcos · Hardness source ↗
- USGS hardness classification
- EPA PFAS benchmarks and implementation
Sources checked October 23, 2026
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Choose the system size, keep useful existing equipment, and review your filtration goals.
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