How does Rosemead's water compare to the national average?

The USA national average is 151 mg/L. Rosemead (≈ 180+ mg/L) is 189 mg/L harder than average.

Rosemead Water Hardness & Quality Report (2026)

Water Hardness

very hard

180+ mg/L

Very Hard

estimated · not lab-verified

Source

reservoir

pH Level

neutral = 7.0

Lead

0.007 mg/L

✓ Below action level

TDS

422.8 mg/L

Est. Daily Cost

$0.91

energy & soap waste

Source: See methodology section below · Updated 2026

very hard180+ mg/LVery Hard · est.

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 Rosemead, your appliances are currently losing 45% efficiency due to mineral buildup.

Appliance	In Rosemead	Soft Water City	Efficiency Loss
Kettle	4.7 yrs	8.5 yrs	-45%
Washing Machine	6.6 yrs	12 yrs	-45%
Water Heater	8.3 yrs	15 yrs	-45%

Regional Water Comparison

How Rosemead compares to its nearest neighbours

City	Hardness	PFAS (ppt)	Risk	Source
▶ Rosemead, California	≈ 180+ mg/L	0 ppt	🔴 Very Hard	reservoir
East San Gabriel, California	≈ 180+ mg/L	6.3 ppt	🔴 Very Hard	mixed
Temple City, California	≈ 120–179 mg/L	5.6 ppt	🟠 Hard	mixed
San Gabriel, California	≈ 180+ mg/L	7.3 ppt	🔴 Very Hard	mixed
South El Monte, California	≈ 180+ mg/L	2.8 ppt	🔴 Very Hard	mixed

National Benchmark

How Rosemead compares to the USA average

Benchmark	Hardness	Appliance Risk
▶ Rosemead	≈ 180+ mg/L	🔴 High
USA National Avg	151 mg/L	🟠 Moderate
Scarsdale Top Rated	0.02 mg/L	🟢 None

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What Makes Rosemead's Water Unique?

Local geology and source profile

Source: ReservoirTDS: 422.8 mg/LpH: 8

Rosemead is served by the San Gabriel Valley Municipal Water Company and local water purveyors within Los Angeles County. The utility draws from a combination of imported surface water and local groundwater sources, including wells tapping the Central Basin aquifer. Treatment facilities process water before distribution to the residential and commercial service area throughout the San Gabriel Valley.

The San Gabriel Valley watershed drains the San Gabriel Mountains and flows across extensive alluvial plains underlain by Quaternary sediments and older Tertiary formations. The Central Basin aquifer supplies significant groundwater to Rosemead and contains mineralized water due to prolonged contact with calcium- and magnesium-rich sedimentary rocks. This hydrogeological setting produces a very hard water supply characteristic of the broader Los Angeles Basin region.

Rosemead's very hard water causes noticeable scale buildup on fixtures, faucets, showerheads, and inside pipes and appliances. Water heaters, dishwashers, and washing machines are particularly vulnerable to mineral accumulation and reduced efficiency. Residents should expect white mineral deposits on glassware and fixtures, reduced soap lather, and potential plumbing maintenance issues over time. Installation of a water softener is strongly recommended to protect appliances and reduce scaling.

Geology & Source: San Gabriel Valley overlies the Central Basin aquifer; Quaternary alluvial sediments rich in calcium and magnesium — semi-arid hydrogeology produces very hard groundwater

Other California Water Reports

East San Gabriel

≈ 180+ mg/L

🔴 Very Hard

Temple City

≈ 120–179 mg/L

🟠 Hard

San Gabriel

≈ 180+ mg/L

🔴 Very Hard

South El Monte

≈ 180+ mg/L

🔴 Very Hard

Report an Issue

Notice an error or missing data? Help us keep this page accurate. If you spot incorrect water hardness, outdated utility info, or missing details, please let us know.

All reports are reviewed by our team. Thank you for supporting data quality!

Frequently Asked Questions

Is Rosemead's water safe to drink?

Yes. Rosemead's water meets all federal safety standards. The hardness is ≈ 180+ mg/L (Very Hard), which is safe to drink. High hardness affects appliances and taste, but poses no health risk.

Do I need a water softener in Rosemead?

At ≈ 180+ mg/L (Very Hard), Rosemead's water will cause significant limescale on kettles, washing machines, and water heaters. A water softener or descaler is strongly recommended to extend appliance lifespan and reduce energy bills by up to 45%.

How does Rosemead compare to the USA average?

The USA national average is 151 mg/L. Rosemead (≈ 180+ mg/L) is 189 mg/L above the national average. The softest major city is Scarsdale at just 0.02 mg/L.

Data Sources & Methodology

Water quality data for Rosemead is derived from geographic and geological modelling of the surrounding region. No federal monitoring station data was available for this location.

Estimated

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.

Estimated

Estimated from regional geology and source water characteristics. pH is correlated with water hardness and local bedrock — values may differ from utility-reported figures.

Estimated

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.

Measured

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.

Modelled

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.

Calculated

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.