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

The USA national average is 151 mg/L. Walnut (≈ 120–179 mg/L) is 1 mg/L softer than average.

Walnut Water Hardness & Quality Report (2026)

Water Hardness

hard

~120–179 mg/L

Hard

estimated · not lab-verified

Source

reservoir

pH Level

neutral = 7.0

Lead

0.007 mg/L

✓ Below action level

TDS

434.7 mg/L

Est. Daily Cost

$0.40

energy & soap waste

Source: See methodology section below · Updated 2026

hard~120–179 mg/LHard · 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 Walnut, your appliances are currently losing 20% efficiency due to mineral buildup.

Appliance	In Walnut	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 Walnut compares to its nearest neighbours

City	Hardness	PFAS (ppt)	Risk	Source
▶ Walnut, California	≈ 120–179 mg/L	0 ppt	🟠 Hard	reservoir
South San Jose Hills, California	≈ 180+ mg/L	3.6 ppt	🔴 Very Hard	mixed
Diamond Bar, California	≈ 180+ mg/L	7.3 ppt	🔴 Very Hard	mixed
Rowland Heights, California	≈ 120–179 mg/L	22.7 ppt	🟠 Hard	reservoir
Covina, California	≈ 180+ mg/L	16.6 ppt	🔴 Very Hard	reservoir

National Benchmark

How Walnut compares to the USA average

Benchmark	Hardness	Appliance Risk
▶ Walnut	≈ 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 Walnut's Water Unique?

Local geology and source profile

Source: ReservoirTDS: 434.7 mg/LpH: 8

Walnut Valley Water District (WVWD) is a public water utility serving the community of Walnut and surrounding areas in Los Angeles County, California. The district sources water from both local groundwater wells and imported surface water, ensuring reliable supply to residential and commercial customers. The utility publishes an annual Consumer Confidence Report (also called the Annual Water Quality Report) detailing all water quality testing and compliance data, available through the district's website or by contacting customer service.

The San Gabriel Valley, where Walnut is located, sits atop complex hydrogeology dominated by Quaternary alluvial aquifers underlain by Tertiary sedimentary formations. These aquifers contain dissolved minerals — primarily calcium and magnesium — leached from limestone, chalk, and other mineral deposits as water percolates through soil and rock. The combination of local groundwater and imported surface water creates a moderately mineralised supply typical of inland Southern California.

At moderately hard levels, residents may notice mineral buildup on fixtures, reduced soap effectiveness, and scale accumulation in water heaters and appliances over time. A water softener is recommended for those sensitive to hard water effects, particularly to extend the lifespan of appliances and improve cleaning efficiency. Regular maintenance of water-using appliances is advisable. WVWD conducts weekly bacteriological testing to ensure safety and regulatory compliance; hardness levels reported in parts per million can be converted to grains per gallon by dividing by 17.1.

Geology & Source: San Gabriel Valley, Los Angeles County; Quaternary alluvial aquifers overlying Tertiary sedimentary formations — calcium and magnesium leached from limestone and mineral deposits; mixed local groundwater and imported surface water yields moderately

Other California Water Reports

South San Jose Hills

≈ 180+ mg/L

🔴 Very Hard

Diamond Bar

≈ 180+ mg/L

🔴 Very Hard

Rowland Heights

≈ 120–179 mg/L

🟠 Hard

Covina

≈ 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 Walnut's water safe to drink?

Yes. Walnut's water meets all federal safety standards. The hardness is ≈ 120–179 mg/L (Hard), which is safe to drink. High hardness affects appliances and taste, but poses no health risk.

Do I need a water softener in Walnut?

At ≈ 120–179 mg/L (Hard), Walnut'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 20%.

How does Walnut compare to the USA average?

The USA national average is 151 mg/L. Walnut (≈ 120–179 mg/L) is 1 mg/L below the national average. The softest major city is Scarsdale at just 0.02 mg/L.

Data Sources & Methodology

Water quality data for Walnut 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.