Three Valleys Mwd
EPA ID: CA1910041 · 0 people served · 22 ZIP codes
Over five tracked years, Three Valleys Mwd has stayed completely violation-free for its 0 residents.
Data: EPA SDWIS Last verified: 2026-04-02
Service Area Map
Coverage area for Three Valleys Mwd Source: EPA SDWIS service area boundaries.
Service area boundary — Grade B
Service Area Demographics
The Three Valleys Mwd serves a community with a median household income of $101,247 and an estimated 926,561 residents across its service area. Approximately 79% of housing stock was built before 1986, which increases the likelihood of lead service lines and older plumbing.
Environmental Justice Note: 48% of the population in this service area is classified as disadvantaged under EPA's EJScreen criteria. Communities with higher disadvantaged populations often face disproportionate environmental and health burdens, including aging water infrastructure and limited resources for remediation.
🌊 Where Does Your Water Come From?
Three Valleys Mwd's water is drawn from rivers, lakes, or reservoirs. Surface water sources are more exposed to agricultural runoff, stormwater, and upstream discharges, but they typically receive more intensive treatment before reaching your tap.
About 2% of homes in Orange County, California rely on private wells rather than public water systems. Private well owners are responsible for their own water testing and treatment.
Superfund Proximity Note: This service area ranks in the 69th percentile nationally for proximity to Superfund (NPL) sites.
Infrastructure Risk
PFAS Detected in Service Area
PFAS ("forever chemicals") have been detected in water serving this system's area. 91 detections recorded. 27 exceed federal EPA limits (4 ppt for PFOA/PFOS). 17 exceed state limits.
Comparable Water Systems
Similar-sized systems in California
Estimated Remediation Costs
Average estimated costs across ZIP codes served by this system
Based on national averages for common remediation projects. Actual costs vary by property. Only issues flagged by EPA, FEMA, or state data for each ZIP code are included.
System Overview
Three Valleys Mwd (EPA ID: CA1910041) is a community water system in California that serves approximately 0 people from surface water sources.
This system provides water to 22 ZIP codes across 16 communities.
Average Home Safety Score: B (83/100)
Based on water quality violations, lead levels, and radon risk across all ZIP codes served by this system.
Violation History
Lead & Copper
EPA Lead and Copper Rule sampling data for ZIP codes served by this system:
| ZIP Code | Lead Level | Exceeds Limit | Sample Date |
|---|---|---|---|
| 91711 | 0.00172 mg/L | No | N/A |
Radon Risk in Service Area
Dominant radon zone for ZIP codes served by this system: Zone 2 (Moderate Risk)
The EPA recommends testing homes in Zone 1 and Zone 2 areas for radon.
Need help with your water quality?
Typical cost: Water test: typically $20–$50 (DIY kit) · Professional inspection: $150–$400
Find the Right Water FilterFree tip: Let cold water run for 2 minutes before drinking — this helps flush lead from your pipes.
ZIP Codes Served
Coverage: Service area ZIP codes sourced from EPA Community Water System Service Area Boundaries v3 (March 2026 release). These ZIPs reflect the actual deployment footprint recorded by CA or modeled from parcel and building-footprint data.
- 90631 — La Habra
- 91702 — Azusa
- 91709 — Chino Hills
- 91711 — Claremont
- 91722 — Covina
- 91723 — Covina
- 91724 — Covina
- 91740 — Glendora
- 91741 — Glendora
- 91744 — La Puente
- 91745 — Hacienda Heights
- 91748 — Rowland Heights
- 91750 — La Verne
- 91759 — Mt Baldy
- 91765 — Diamond Bar
- 91766 — Pomona
- 91767 — Pomona
- 91768 — Pomona
- 91773 — San Dimas
- 91789 — Walnut
- 91791 — West Covina
- 91792 — West Covina
Data Sources
This report uses public data from the EPA Safe Drinking Water Information System (SDWIS). View the full compliance record for Three Valleys Mwd (CA1910041) on EPA.gov.
Frequently Asked Questions
Is Three Valleys Mwd water safe to drink?
Based on EPA records, Three Valleys Mwd has no recorded violations in the past 5 years — a positive indicator of water quality management.
How many people does Three Valleys Mwd serve?
Three Valleys Mwd serves approximately 0 people across 22 ZIP codes in California.
Where does Three Valleys Mwd get its water?
The primary water source is surface water.
Water Source & Treatment
Where this water originates and how it's treated before reaching your tap.
Source: Three Valleys Municipal Water District Consumer Confidence Report.
ZipCheckup is not affiliated with this water utility. Treatment and source data are sourced from the utility's published CCR filings.
Treatment regime
How this utility classifies its treatment process and what each reported treatment chemical does.
Treatment chemicals and what each one does
Chemical names are reported verbatim by the utility. Purpose categories are ZipCheckup annotations based on standard drinking-water treatment practice.
Treatment classification and chemical list sourced from Three Valleys Municipal Water District Consumer Confidence Report.
Treatment intensity is a ZipCheckup-derived classification based on the chemicals and processes the utility reports. Chemicals and contamination sources are taken verbatim from the utility's CCR filing. Routine federal monitoring and contaminant testing shown elsewhere on this page determine whether the water meets safety standards, not the treatment classification.
PFAS Substances Detected in This System
This water system's Consumer Confidence Report disclosed the following PFAS compounds. Levels are from the utility's most recent reporting cycle.
In April 2024, EPA finalized the first National Primary Drinking Water Regulation for six PFAS. Public water systems have until 2029 to comply. EPA — PFAS regulation overview →
Source: Consumer Confidence Report disclosed by Three Valleys Municipal Water District.
ZipCheckup is not affiliated with this water utility. PFAS detection data is sourced from public Consumer Confidence Reports filed by the utility itself.
Aesthetic water quality
These measurements describe the look, taste, and feel of the water this utility delivers. They are not contaminant violations — they sit alongside federal Secondary Maximum Contaminant Levels (SMCLs) which the EPA publishes as non-enforceable guidance.
Aesthetic measurements from Three Valleys Municipal Water District Consumer Confidence Report.
Aesthetic measurements are reported by the utility from its annual sampling. EPA Secondary MCLs are advisory thresholds — values outside them indicate aesthetic concerns such as taste or appearance, not health violations. Federal contaminant testing is shown in the sections above.
Hard water detected in Three Valleys Municipal Water District
Your utility reported water hardness of 272 ppm CaCO₃ (15.9 grains per gallon) in its most recent Consumer Confidence Report. This is in the very hard range and may cause scale buildup, reduced appliance lifespan, and dry skin or hair.
There are three common approaches to treating hard water: salt-based ion-exchange softeners (most effective, require salt refills), salt-free conditioners (lower maintenance, scale prevention only), and reverse osmosis at the kitchen sink (cooking and drinking water only). Aquasana, EcoWater, Pelican, and SpringWell are among the major US brands.
Paid Partner. ZipCheckup earns commission on Aquasana purchases. We do not test water or verify product effectiveness for specific hardness levels — manufacturer claims are theirs alone. Consult a certified water-quality professional for personalized advice.
Hardness data parsed from this utility's most recent Consumer Confidence Report. Severity bands per USGS hard water classification.