REDWOOD CITY, California Tap Water Quality

93,761 people served · 3 water systems

Good

REDWOOD CITY, California is a mid-sized community with 93,761 residents served by 3 public water systems. Water service covers ZIP code 94063.

REDWOOD CITY's water utilities have recorded a small number of EPA health-based violations in the last five years. These were resolved through standard corrective action.

EPA reporting identifies Haloacetic Acids (HAA5) among the regulated contaminants associated with REDWOOD CITY's recent health-based violations. Each contaminant has different sources, health implications, and recommended mitigation steps — links to the full EPA reference for each are listed alongside the violation history below.

Last updated: 2026-05-18 · Source: EPA SDWIS

Location

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Centered on ZIP-code centroids of water systems serving this city.

ZIP Codes Served

94063

Health-Based Violations (Last 5 Years)

EPA Maximum Contaminant Level exceedances reported by water systems serving REDWOOD CITY. Each entry explains the contaminant, the health risk, and recommended precautions, and links to a full guide.

Haloacetic Acids (HAA5)disinfectant

EPA Code 2456 · Maximum Contaminant Level Exceedance

violations

EPA Limit

0.06 mg/L

Last Reading

.064 MG/L

First Reported

Jan 2025

Most Recent

Jan 2025

What this violation means

Haloacetic Acids (HAA5) are the second major group of disinfection byproducts after TTHMs. They form by the same mechanism — chlorine reacting with organic matter — and pose similar long-term cancer risks. Utilities are required to test quarterly at distribution-system locations to track HAA5 levels.

Recommended precautions

→Activated carbon filtration removes most HAA5.
→Reverse osmosis is highly effective.
→Unlike TTHMs, HAA5 do not significantly off-gas. Use treatment rather than aeration.
→Long-term ingestion is the primary concern, not short-term skin contact.

Read the complete guide to Haloacetic Acids (HAA5)

Source: EPA Safe Drinking Water Information System (SDWIS). Health-based violations only. Older violations may have been resolved; check your utility's most recent Consumer Confidence Report for current status.

Water Systems Serving REDWOOD CITY

COUNTY SERVICE AREA 11

PWSID: CA4100582

642 served

COUNTY SERVICE AREA 7

PWSID: CA4100509

300 served

2 violations

CITY OF REDWOOD CITY

PWSID: CA4110022

92,819 served

What Can You Do?

✅ Request your utility's annual Consumer Confidence Report (CCR) — required by law.
✅ Use an NSF-certified water filter if violations involve lead, arsenic, or PFAS.
✅ Run cold water for 30 seconds before drinking if you have older plumbing (reduces lead).
✅ Check back monthly — we update data from the EPA every 30 days.

About this data

This overview reflects EPA SDWIS data published as of 2026-05-18. It covers active Community Water Systems (CWS) that exceeded federal Maximum Contaminant Levels during the past five-year EPA reporting window. For up-to-the-minute information, request a current Consumer Confidence Report from your utility, or review the EPA's public dashboard.

Frequently Asked Questions

Is REDWOOD CITY, California tap water safe to drink?▼

This city's water had minor EPA violations in the last 5 years.

How many EPA violations does REDWOOD CITY have?▼

REDWOOD CITY has 2 EPA health-based water violations in the last 5 years across 3 water systems serving 93,761 people.

What contaminants have been found in REDWOOD CITY water?▼

The following EPA-regulated contaminants have been detected: 2456. View details about each contaminant, health effects, and recommended precautions above in the violations table.

Should I use a water filter in REDWOOD CITY?▼

Using an NSF-certified water filter is recommended if your area has violations involving lead, arsenic, or PFAS. For other contaminants, consult your local water utility. Check the annual Consumer Confidence Report (CCR) for detailed guidance.

What should I do if there are violations in REDWOOD CITY?▼

Request your water utility's annual Consumer Confidence Report (CCR), which is required by the EPA. Follow the utility's guidance on boil water advisories. Run cold water for 30 seconds before drinking if you have older plumbing. Use an NSF-certified filter if needed based on your water system's violations.