Hardness
Moderately hard to very hard103–236mg/L as CaCO₃
Range of six source averages
USGS: hard >120; very hard >180 mg/L
Source averages ≈ 6.0–13.8 gpg. Full source range: 78–280 mg/L. Your blend can differ.
2025
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Your local water, explained
Los Angeles County water reports & provider guide
LADWP is the first detailed system covered. Long Beach and Pasadena publish separate reports.
The detailed results below belong to LADWP. Its source averages span moderately hard to very hard water, so the supplying source matters when planning scale control.
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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 25, 2026
Choose the right utility report
The figures below are provider-specific. They are not a countywide average.
| Utility | Hardness | Hardness source |
|---|---|---|
| 103–236 mg/L · Moderately hard to very hard | 2025 reported hardness |
Showing utility report
Los Angeles Department of Water and Power (LADWP)
2025 utility report; each result retains its sampling year
Only use these results if Los Angeles Department of Water and Power (LADWP) is the supplier on your bill. Other utilities and private wells need their own data.
Your water at a glance
See the amount, the comparison and what it means. “Below” refers to the stated benchmark, not zero risk.
Disinfectant residual
Below 4 mg/L MRDL1.7mg/L
Total chlorine · highest running annual average
LADWP uses chloramines; this is total residual, not a free-chlorine-only reading.
2025
View source ↗TTHM
Below 80 ppb MCL33.8ppb
Highest locational running annual average
2025
View source ↗HAA5
Below 60 ppb MCL13.4ppb
Highest locational running annual average
2025
View source ↗Fluoride
Below California 2 mg/L MCL0.7mg/L
Citywide average · range 0.2–0.8
Dedicated fluoride treatment is a separate selection.
2025
View source ↗Lead
Below 15 ppb action level<5ppb
90th percentile · 105 sampled taps
3 of 105 sites exceeded 15 ppb. A low system percentile does not rule out lead at an individual home.
2023
View source ↗Arsenic
Below 10 ppb MCL<2–3.3ppb
Range of source averages · overall range <2–7.0
The legal limit differs from California’s 0.004 ppb health goal.
2025
View source ↗PFAS
Below reporting limitsNot detected
Tested PFAS at distribution entry points
Historical UCMR5 results are not a current home test or proof of zero PFAS.
Dec 2023–Sep 2024
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 | 103–236 mg/L as CaCO₃Range of six source averages | 2025View source ↗ | Moderately hard to very hardSource averages ≈ 6.0–13.8 gpg. Full source range: 78–280 mg/L. Your blend can differ. |
| Disinfectant residual | 1.7 mg/LTotal chlorine · highest running annual average | 2025View source ↗ | Below 4 mg/L MRDLLADWP uses chloramines; this is total residual, not a free-chlorine-only reading. |
| TTHM | 33.8 ppbHighest locational running annual average | 2025View source ↗ | Below 80 ppb MCL |
| HAA5 | 13.4 ppbHighest locational running annual average | 2025View source ↗ | Below 60 ppb MCL |
| Fluoride | 0.7 mg/LCitywide average · range 0.2–0.8 | 2025View source ↗ | Below California 2 mg/L MCLDedicated fluoride treatment is a separate selection. |
| Lead | <5 ppb90th percentile · 105 sampled taps | 2023View source ↗ | Below 15 ppb action level3 of 105 sites exceeded 15 ppb. A low system percentile does not rule out lead at an individual home. |
| Arsenic | <2–3.3 ppbRange of source averages · overall range <2–7.0 | 2025View source ↗ | Below 10 ppb MCLThe legal limit differs from California’s 0.004 ppb health goal. |
| PFAS | Not detected Tested PFAS at distribution entry points | Dec 2023–Sep 2024View source ↗ | Below reporting limitsHistorical UCMR5 results are not a current home test or proof of zero PFAS. |
| Nitrate as nitrogen | <0.4 mg/L as NAll six source averages · highest reported sample 1.4 | 2025View source ↗ | Below 10 mg/L MCL |
| Copper | 529 ppb90th percentile · 105 sampled taps | 2023View source ↗ | Below 1,300 ppb action level0 of 105 sites exceeded the action level. |
| Total dissolved solids | 234–545 mg/LRange of source averages · full range 187–625 | 2025View source ↗ | Below 1,000 mg/L secondary MCLAesthetic standard; TDS is not a hardness measurement. |
| Hardness — Los Angeles Aqueduct Filtration Plant | 103 mg/L as CaCO₃Source average · range 96–117 | 2025View source ↗ | Moderately hardCalculated average: 6.0 gpg. Use the report’s service-area map to understand your blend. |
| Hardness — Northern Combined Wells | 115 mg/L as CaCO₃Source average · range 78–151 | 2025View source ↗ | Moderately hardCalculated average: 6.7 gpg. Use the report’s service-area map to understand your blend. |
| Hardness — Southern Combined Wells | 116 mg/L as CaCO₃Source average · range 83–159 | 2025View source ↗ | Moderately hardCalculated average: 6.8 gpg. Use the report’s service-area map to understand your blend. |
| Hardness — MWD Weymouth Plant | 234 mg/L as CaCO₃Source average · range 189–280 | 2025View source ↗ | Very hardCalculated average: 13.7 gpg. Use the report’s service-area map to understand your blend. |
| Hardness — MWD Diemer Plant | 236 mg/L as CaCO₃Source average · range 191–280 | 2025View source ↗ | Very hardCalculated average: 13.8 gpg. Use the report’s service-area map to understand your blend. |
| Hardness — MWD Jensen Plant | 140 mg/L as CaCO₃Source average · range 137–142 | 2025View source ↗ | HardCalculated average: 8.2 gpg. Use the report’s service-area map to understand your blend. |
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.
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Source water. Los Angeles Aqueduct, local groundwater and Metropolitan Water District supplies from the State Water Project and Colorado River Aqueduct.
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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A city report cannot establish a well’s water quality. Well-water treatment depends on your test results and site conditions.
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More about your local water
What this means for your home
The county includes independent city utilities and other suppliers. A Los Angeles mailing address alone does not establish LADWP service. LADWP itself blends several sources, so hardness varies within its service area.
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
Can I use one report for all of Los Angeles County?
No. The detailed figures here belong only to Los Angeles Department of Water and Power (LADWP). Use the other-provider links for a different supplier, and current testing for a private well.
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.
- Los Angeles Department of Water and Power (LADWP) ↗2025 utility report; each result retains its sampling year
- USGS hardness classification
- EPA PFAS benchmarks and implementation
Sources checked October 25, 2026
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