South El Monte, CA Water Safety: 63/100 (2026)
1 ZIP code · 5 water systems · Updated 2026-06-03
Water monitoring across South El Monte paints a mid-range picture within CA — solid compliance in some service zones, documented concerns in others. Most violations on record are concentrated in specific areas, and the overall grade has held in the middle tier without major shifts in recent monitoring cycles.
How South El Monte Compares
Data: EPA SDWIS Last verified: 2026-06-03
South El Monte Water: The Quick Version
- Homes built before 1986: 81% — older plumbing may contain lead solder.
- Estimated remediation: $2,200 per household.
- CDC health risk index: 10.71.
Water Systems Serving South El Monte
With 3 utilities splitting service in South El Monte, CA, water accountability is distributed across 5 systems on the federal record.
Overview
We track water quality and home safety data for 1 ZIP code in South El Monte, California (population ~41,716), covering 5 community water systems serving approximately 325,821 people region-wide.
No EPA violations recorded across any ZIP codes in South El Monte — an excellent indicator of water quality.
Home Safety Score
Average Home Safety Score for South El Monte: C (63/100)
The score combines three factors:
| Factor | What It Measures |
|---|---|
| Water Quality | EPA violations and compliance history |
| Lead Levels | 90th percentile lead concentration vs EPA action level |
| Radon Risk | EPA radon zone classification |
Water Sources
South El Monte water systems draw from: Groundwater.
Lead & Copper
- Lead data: not yet available for South El Monte
- 0 ZIP codes exceed the EPA lead action level
Radon Risk
Dominant radon zone: Zone 2 (Moderate Risk)
The EPA recommends testing homes in Zone 1 and Zone 2 areas for radon.
Areas with No Violations
| ZIP Code | Safety Score | System | Population |
|---|---|---|---|
| 91733 | C | SAN GABRIEL VALLEY WATER CO.-EL MONTE | 248,000 |
All ZIP Codes in South El Monte
- 91733 [C]
Data Sources
- Water quality: EPA Safe Drinking Water Information System (SDWIS)
- Lead/copper: EPA Lead and Copper Rule sampling data
- Radon: EPA Map of Radon Zones
Updated daily.
CDC Health Data for South El Monte
Source: CDC PLACES (County-level estimates). Water contamination can correlate with respiratory and chronic health conditions.
Compared to National Average
Vertical line = national average. ■ Above national · ■ Below national
How Old Is South El Monte's Housing Stock?
With 81% of homes built before 1986, lead solder in plumbing is a potential concern. The EPA banned lead solder in 1986, but many older homes retain original plumbing.
Source: U.S. Census Bureau American Community Survey (ACS).
Housing Age Profile
Pre-1986 plumbing is not a rare legacy case in South El Monte — it's the dominant profile. The median build year of 1950 indicates a housing stock where lead-soldered copper joints are a common structural feature of residences across the city.
Over half of homes in South El Monte were built before 1986, when lead solder was banned. Older plumbing may leach lead into drinking water, especially with corrosive water chemistry.
Source: U.S. Census Bureau ACS B25034.
South El Monte: Remediation Cost in Perspective
Equity impact data for South El Monte lands in the favorable tier — remediation claims a small slice of what properties here are worth.
Remediation costs in South El Monte are relatively low compared to home values. The $1,200–$3,400 estimated range is a small fraction of median property value. Home values are 19% below the California average.
Protecting Children from Lead in South El Monte
Why children are most at risk: The CDC states there is no safe level of lead exposure for children. Children under 6 absorb lead more readily than adults, and even low levels can cause developmental delays, learning difficulties, and behavioral problems.
Despite citywide averages serving as the standard public reference point, those aggregates cannot resolve what is happening at one specific faucet — and where 81% of South El Monte homes come from before the solder rule or where utility samples sit at or above the action mark, the gap between system data and faucet reality matters more than it does in lower-exposure communities. An in-home draw closes that gap, with certified filtration through retailer networks available where confirmed faucet results warrant additional measures.
Sources: EPA Lead and Copper Rule, U.S. Census Bureau ACS, CDC childhood lead poisoning prevention guidelines.
Climate-Related Water Risk for South El Monte
Across the NFIP's long tracking period, South El Monte shows 2 claims and 100% of ZIP codes within FEMA-designated flood zones — figures that place it in moderate flood exposure territory. At this level, the water-quality implications of flooding — contaminated wells, stressed treatment intake, distribution backflow — move from theoretical edge cases to genuine periodic risks, particularly during higher-severity events.
South El Monte has a moderate flood history with 2 FEMA claims averaging $1,455 per payout. 100% of ZIP codes fall within FEMA flood zones. Flood events can contaminate drinking water and overwhelm treatment systems.
How flooding affects water quality: Flood events can introduce sewage, agricultural runoff, and industrial chemicals into water supplies. Even after floodwaters recede, contamination can persist in wells and aging infrastructure. Flood damage can add significantly to the estimated <strong>$2,200</strong> remediation cost per household.
Residents in flood-prone areas should consider flood insurance even outside FEMA zones — over 25% of flood claims come from low-to-moderate risk areas. After any flood event, test your water before drinking.
Source: FEMA National Flood Insurance Program (NFIP) claims data, FEMA flood zone designations.
What You Can Do in South El Monte
- Test your water at home. City-level data shows averages — your tap may differ. NSF-certified test kits cost $20-40 and give results in days.
- Install a certified water filter. An NSF-certified pitcher or under-sink filter removes most common contaminants.
- Check your home's plumbing. With 81% of homes built before 1986, lead solder is a real possibility.
Deep Dive Reports
Detailed analysis for South El Monte, CA