Monrovia Water Hardness & Quality Report (2026)
Water Hardness
~120–179 mg/L
Hardestimated · not lab-verified
Source
groundwater
pH Level
7.2
neutral = 7.0
Lead
0.001 mg/L
✓ Below action level
TDS
68.5 mg/L
Est. Daily Cost
$0.40
energy & soap waste
Source: See methodology section below · Updated 2026
0–60
mg/L
Soft
61–120
mg/L
Moderately Hard
121–180
mg/L
Hard
180+
mg/L
Very Hard
Appliance Damage Report
In Monrovia, your appliances are currently losing 20% efficiency due to mineral buildup.
| Appliance | In Monrovia | Soft Water City | Efficiency Loss |
|---|---|---|---|
| Kettle | 6.8 yrs | 8.5 yrs | -20% |
| Washing Machine | 9.6 yrs | 12 yrs | -20% |
| Water Heater | 12 yrs | 15 yrs | -20% |
Regional Water Comparison
How Monrovia compares to its nearest neighbours
| City | Hardness | PFAS (ppt) | Risk | Source |
|---|---|---|---|---|
| ▶ Monrovia, California | ≈ 120–179 mg/L | 62.5 ppt | 🟠 Hard | groundwater |
| Duarte, California | ≈ 180+ mg/L | 4.6 ppt | 🔴 Very Hard | mixed |
| Arcadia, California | ≈ 180+ mg/L | 29.2 ppt | 🔴 Very Hard | groundwater |
| Sierra Madre, California | 85.5 mg/L | 0 ppt | 🟡 Moderately Hard | reservoir |
| Temple City, California | ≈ 120–179 mg/L | 5.6 ppt | 🟠 Hard | mixed |
National Benchmark
How Monrovia compares to the USA average
| Benchmark | Hardness | Appliance Risk |
|---|---|---|
| ▶ Monrovia | ≈ 120–179 mg/L | 🟠 Moderate |
| USA National Avg | 151 mg/L | 🟠 Moderate |
| Scarsdale Top Rated | 0.02 mg/L | 🟢 None |
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What Makes Monrovia's Water Unique?
Local geology and source profile
MONROVIA-CITY, WATER DEPT. supplies drinking water to 37,787 residents across Monrovia in Los Angeles County, California. The utility uses a mixed supply of local groundwater extracted from wells in the San Gabriel Valley and purchased surface water from the Metropolitan Water District of Southern California, sourced via the California State Water Project and Colorado River Aqueduct. Treatment involves air stripping and disinfection with hypochlorite at the main facility at 600 S. Mountain Ave, serving a 9,859-connection system.
Local groundwater relies on the Raymond and Central groundwater basins, recharged by mountain runoff percolating through fractured granitic and metamorphic bedrock of Mesozoic age — including gneiss and schist — before depositing into Quaternary alluvial aquifers. These formations dissolve calcium and magnesium from limestone and dolomite fragments in the basin fill, yielding a hard supply. Imported surface water traverses varied terrains including ancient limestone outcrops of the San Gabriel Mountains, further adding to the mineral content and hard character of the blended supply.
Hard water in Monrovia promotes scale buildup in pipes, water heaters, dishwashers, and washing machines, reducing efficiency and lifespan. Soap lathering is diminished, leading to residue on dishes and skin dryness; regular deliming of appliances and flushing water heaters is advised. A water softener is recommended to mitigate these effects and extend equipment life. Per the 2024 Consumer Confidence Report, water quality meets all EPA and state standards with no violations; of 70 chemicals tested, 16 were detected but none exceeded MCLs. Lead testing at schools showed non-detectable levels, and PFAS testing has been ongoing since 2020.
Geology & Source: San Gabriel Valley; Raymond Basin and Central Basin Quaternary alluvial aquifers — limestone/dolomite fragments yield hard groundwater; blended with Metropolitan Water District surface water from Colorado River Aqueduct
Other California Water Reports
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Frequently Asked Questions
Is Monrovia's water safe to drink?
Do I need a water softener in Monrovia?
How does Monrovia compare to the USA average?
Data Sources & Methodology
Water quality data for Monrovia is derived from geographic and geological modelling of the surrounding region. No federal monitoring station data was available for this location.
Water Hardness
Modelled estimate based on state-level USGS geological survey data for this region. No direct USGS Water Quality Portal measurement was matched to this city — the value reflects a statistical range calibrated to the state's dominant rock types and typical source water characteristics.
pH
Estimated from regional geology and source water characteristics. pH is correlated with water hardness and local bedrock — values may differ from utility-reported figures.
TDS — Total Dissolved Solids
Estimated using a derived ratio from water hardness and regional conductance profiles. TDS in natural water correlates strongly with total mineral content including hardness ions.
PFAS — Perfluoroalkyl and Polyfluoroalkyl Substances
EPA UCMR5 (5th Unregulated Contaminant Monitoring Rule, 2023–2025) — sum of PFAS compounds detected at the public water system serving this city. A value of 0 indicates the system was sampled with no detection above reporting limits.
Lead
Modelled estimate based on the EPA Lead and Copper Rule 90th-percentile tap-sample methodology. No publicly available per-city lead dataset with sufficient national coverage exists. Values are a conservative baseline derived from city population tier and infrastructure age — all estimates are maintained below the EPA action level of 0.015 mg/L.
Appliance Lifespan
Calculated from water hardness using a linear degradation model. Baseline lifespans represent soft-water performance (kettle: 8.5 yrs, washing machine: 12.0 yrs, water heater: 15.0 yrs). Hard water mineral scale progressively reduces operational life in direct proportion to hardness concentration.