Guide

How to check California tap water quality by ZIP

A plain-English walkthrough for homeowners who want a ZIP-based public water system report — not a faucet lab test.

Honest framing: TapCheck CA matches your ZIP to a public water system using California service-area data where available. Reports summarize curated detections from SDWIS monitoring extracts. Educational only — not medical advice, not a faucet lab test, and not affiliated with EWG or any utility.

ZIP report vs lab test

A ZIP report tells you what your matched public water system has recently detected in monitoring data, compared with legal limits and California health guidelines. It is free and fast.

A lab test of your faucet measures water at your tap. That can catch home plumbing issues (especially lead) that utility monitoring will not show. Use a ZIP report first to understand your utility’s picture; use a lab test if you need faucet-specific answers.

Steps

  1. Enter your California ZIP

    Start on the TapCheck home page and type your five-digit ZIP. You’ll get a matched public water system report when data is available.

  2. Confirm the name on your bill

    If more than one utility serves the area, pick the name that matches your water bill. Overlaps are normal in some cities.

  3. Read MCL and PHG side by side

    EPA MCLs are legal limits. California PHGs are stricter health guidelines. Seeing both helps you understand “legal” vs “health goal” without jargon overload. More detail on how to read your report and methodology.

  4. Optional: ask a local installer

    If you want help comparing filter options, use “Ask a local installer.”

Helpful links

Short FAQ

Is a ZIP report the same as a lab test of my faucet?

No. A ZIP report summarizes curated detections from California public water system monitoring for a matched utility. A faucet lab test measures water at your tap, including home plumbing. They answer different questions.

What should I do after I enter my ZIP?

Confirm the utility name matches your water bill. Then read detections against EPA legal limits (MCLs) and California public health goals (PHGs). Optionally ask a local installer about filter options — we do not show plumber pricing here.

What if my ZIP shows more than one utility?

Overlapping service areas show a chooser. Pick the name on your bill. Details are on the methodology page.

Where can I learn more?

See the FAQ, methodology, city guides, and the Inland Empire region guide.

Check my ZIP More FAQ