Drinking Water Safety Guide: How to Tell If Your Tap Water Is Safe
Your tap water passes through dozens of regulations before reaching your glass — but EPA violations are still common. This guide walks you through everything you need to know to judge your water's safety, in plain English.
1. Check your city's water quality
The fastest way to gauge your tap water is to check the EPA's Safe Drinking Water Information System (SDWIS), which tracks every health-based violation by every public water system in the United States. We make that data searchable by city, state, or ZIP.
Search your city →2. Read your Consumer Confidence Report (CCR)
Every July, your water utility is required by EPA law to mail or email you a Consumer Confidence Report — sometimes called a Water Quality Report or Annual Drinking Water Report. It lists every regulated contaminant tested for, the levels detected, and how those levels compare to EPA limits (called Maximum Contaminant Levels, or MCLs).
What to look for in your CCR:
- Any contaminant flagged as a "violation"
- Detected levels close to (within 50% of) the MCL
- Lead in first-draw samples above 5 ppb
- Source water (groundwater vs. surface water vs. purchased)
- Treatment processes used (disinfection, filtration)
3. Understand the most common contaminants
Of the 15+ EPA-regulated contaminants, a small handful cause the majority of health-based violations nationwide. Click any to learn the health effects, sources, and treatment options.
Lead
EPA limit: 0.015 mg/L (action level)
Developmental delays in children, kidney problems, and high blood pressure in adults.
Arsenic
EPA limit: 0.01 mg/L
Increased risk of cancer (skin, bladder, lung), skin damage, and circulatory problems.
PFAS (PFOA & PFOS)
EPA limit: 0.000004 mg/L (4 ppt)
Cancer, thyroid disruption, immune system effects, and reproductive harm.
4. Decide if you need a filter
Not every household needs a filter. But if your city has any of the following violations, a certified filter is the cheapest insurance you can buy:
| If your water has... | Look for filter rated... |
|---|---|
| Lead | NSF/ANSI 53 |
| PFAS / "forever chemicals" | NSF/ANSI 401 or reverse osmosis |
| Arsenic | NSF/ANSI 58 (reverse osmosis) |
| Nitrates | Reverse osmosis or ion exchange |
| Chlorine taste | NSF/ANSI 42 (basic carbon) |
| Disinfection byproducts (THMs) | NSF/ANSI 53 carbon block |
Always verify the filter is independently certified — the NSF logo + standard number should appear on the box. Replace cartridges on schedule, or filters do more harm than good.
5. Test your own water
EPA testing happens at the source — not at your tap. If you live in an older home (built before 1986), have a private well, or notice taste / odor / discoloration, get your water tested.
- Free utility tests: Many utilities will test for lead at no cost. Call and ask.
- Certified labs: Find an EPA-certified lab in your state at epa.gov/dwlabcert.
- At-home test kits: Good for screening (chlorine, hardness, pH). Not a substitute for lab tests on lead, arsenic, or PFAS.
- Private wells: The EPA does not regulate private wells. Test annually for bacteria and every 2-3 years for chemicals.
Frequently asked questions
How do I know if my tap water is safe to drink?▼
Check your city's water quality on TapSafeWater for current EPA violations, then read your utility's annual Consumer Confidence Report (CCR), which they are legally required to mail every July. If your area has reported lead, arsenic, PFAS, or nitrate violations, use an NSF-certified filter.
What is a Consumer Confidence Report (CCR)?▼
A CCR is the annual water quality report your utility is required by EPA law to provide every July. It lists contaminants detected, their levels, and how they compare to EPA limits (MCLs).
What is an EPA MCL?▼
MCL stands for Maximum Contaminant Level — the highest level of a contaminant the EPA allows in drinking water. When a water system exceeds an MCL, it counts as a health-based violation and the utility must notify the public and take corrective action.
Should I buy a water filter?▼
If your water system has EPA violations involving lead, arsenic, PFAS, nitrates, or radium, use an NSF-certified filter. Look for NSF/ANSI 53 (health contaminants), NSF/ANSI 58 (reverse osmosis), or NSF/ANSI 401 (emerging contaminants like PFAS). Choose the standard that matches your specific contaminants.
Is bottled water safer than tap water?▼
Not necessarily. Bottled water is regulated by the FDA, which has fewer disclosure requirements than the EPA. Many bottled waters are just filtered tap water. A certified home filter on tested tap water is often safer and cheaper.
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