Throughout Aliso Viejo and across its water systems, EPA compliance data for CA shows above-average performance — violations are minimal, none of the tracked systems have recorded repeated MCL exceedances in recent cycles, and the safety picture has held steady across multiple reporting periods.

Data: EPA SDWIS Last verified: 2026-06-03

Overview

We track water quality and home safety data for 2 ZIP codes in Aliso Viejo, California (population ~52,645), covering 3 community water systems serving approximately 666,836 people region-wide.

No EPA violations recorded across any ZIP codes in Aliso Viejo — an excellent indicator of water quality.

Home Safety Score

Average Home Safety Score for Aliso Viejo: B (70/100)

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

Aliso Viejo water systems draw from: Surface water.

Lead & Copper

• Lead data: not yet available for Aliso Viejo
• 0 ZIP codes exceed the EPA lead action level

Radon Risk

Dominant radon zone: Zone 3 (Low Risk)

• Zone 1 (High): 0 ZIP codes
• Zone 2 (Moderate): 0 ZIP codes
• Zone 3 (Low): 2 ZIP codes

Areas with No Violations

All ZIP Codes in Aliso Viejo

• 92656 [B]
• 92698 [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.

Cost Context: What Remediation Means for Aliso Viejo Homeowners

What does remediation cost in financial context for Aliso Viejo homeowners? Proportionally very little — the equity share here is low, and addressing documented issues is a manageable planning question rather than a material financial burden.

Median Home Value

$849,900

Est. Remediation

$1,700

Remediation as % of home value 0.2%

Remediation costs in Aliso Viejo are relatively low compared to home values. The $1,100–$2,600 estimated range is a small fraction of median property value. Home values are 15% above the California average.

Flood & Climate Risk in Aliso Viejo

Over the multi-decade window covered by the National Flood Insurance Program, Aliso Viejo has accumulated 4 claims — a total that suggests more than isolated flood exposure. With 50% of ZIP codes in designated flood zones, the water-quality implications of flooding move from hypothetical to periodically relevant: treatment intake can be compromised, wells can be infiltrated, and distribution backflow can occur.

4

Total FEMA Flood Claims

$4,288

Avg Claim Payout

50%

ZIPs in FEMA Flood Zones

Aliso Viejo has a moderate flood history with 4 FEMA claims averaging $4,288 per payout. 50% 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>$1,700</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.