Is US Tap Water Safe to Drink?
What the data really says about American tap water, and how to know about yours.
Jun 2, 2026 Independent drinking water reference
Know what’s in your water.
Search a contaminant, compare home filters, and understand the rules that set the standards, all from public EPA, USGS, and CDC data.
Searches Clear Tap’s contaminant reference below. For your specific utility’s data, see how to read your water report.
Built from public data: EPAUSGSCDCNSF / ANSI Last reviewed June 2026
01
All safety guides →The contaminant reference
Common drinking water contaminants, their federal limit, and the health-based goal. Tap any row for the full guide.
| Contaminant | Category | Federal limit | Health goal | |
|---|---|---|---|---|
| Lead | Metal | 10 ppb (action level) | Zero | → |
| PFOA / PFOS (PFAS) | Industrial | 4 ppt | Zero | → |
| Arsenic | Naturally occurring | 10 ppb | Zero | → |
| Nitrate | Agricultural | 10 mg/L | 10 mg/L | → |
| Copper | Metal | 1.3 mg/L (action level) | 1.3 mg/L | → |
| Trihalomethanes (TTHM) | Disinfection byproduct | 80 ppb | Varies | → |
| Haloacetic acids (HAA5) | Disinfection byproduct | 60 ppb | Varies | → |
| Chlorine (residual) | Disinfectant | 4.0 mg/L (MRDL) | 4.0 mg/L | → |
| E. coli & coliform bacteria | Biological | Zero (MCL) | Zero | → |
| Legionella | Biological | Treatment technique | Zero | → |
| Microplastics | Emerging | No federal limit | Not set | → |
02
Where does your water come from?
Your water source decides what to worry about and who is responsible for testing it.
Public / city water
You get an annual report
Your utility tests the water and must publish a yearly Consumer Confidence Report. Learn how to read it and what the numbers mean.
Private wellTesting is on you
Wells are not federally regulated, so no one tests your water but you. Here is what to test for and how often.
03
Start here
Three guides that answer the questions most people actually have.
01
Water Safety & Contaminants
Is US Tap Water Safe to Drink?
What the data really says about American tap water, and how to know about yours.
02
Purification & Filtration
Home Water Filters Explained: What Removes What
A plain-English map of every filter type and the contaminants each handles.
03
Regulation & Data
The Safe Drinking Water Act, Explained
The 1974 law behind every US tap, and what it does and does not cover.
04
All filtration guides →Compare home filters
No filter removes everything. Match the method to the contaminant you actually have.
Activated carbon
Most common
- Chlorine, taste & odor
- Many organic chemicals
- Lead & PFAS (certified blocks)
Reverse osmosis
Most thorough
- Lead, arsenic, nitrate
- PFAS & dissolved salts
- Broadest range
Distillation
Broad spectrum
- Metals & minerals
- Nitrate & arsenic
- Kills microbes
UV purification
Microbes only
- Bacteria & viruses
- Parasites
- No chemical removal
05
View all →Water Safety & Contaminants
Lead in Drinking Water: Risks and What to Do
Where lead comes from, why there is no safe level, and how to protect your home.
May 20, 2026PFAS ‘Forever Chemicals’ in Drinking Water
What PFAS are, the new EPA limits, and how to reduce them at home.
May 12, 2026Arsenic in Drinking Water
A natural contaminant with real health risks, especially in private wells.
Apr 28, 2026Nitrate in Drinking Water
An agricultural contaminant that is a serious risk for infants and wells.
Apr 15, 2026Chlorine and Disinfection Byproducts
Why we disinfect water, and the trade-off of byproducts like THMs.
Mar 30, 2026Copper in Drinking Water
How copper gets into tap water from your own plumbing, and the limits.
Mar 12, 2026Microplastics in Drinking Water
What we know, what is still uncertain, and what filtration helps.
Feb 24, 2026Bacteria and Waterborne Pathogens
E. coli, Legionella, and the bugs that boil-water notices target.
Feb 10, 202606
View all →Purification & Filtration
Home Water Filters Explained: What Removes What
A plain-English map of every filter type and the contaminants each handles.
Jun 9, 2026Reverse Osmosis Systems: A Complete Guide
The most thorough home treatment, how it works, and its trade-offs.
May 26, 2026Activated Carbon Water Filters
The most common filter, what it removes, and what it does not.
May 5, 2026Water Distillation Explained
How distillers work and when they make sense for a household.
Apr 21, 2026UV Water Purification
Ultraviolet treatment for pathogens, and why it is not a filter.
Apr 7, 2026How to Choose a Water Filter
A step-by-step framework built around what is actually in your water.
Mar 20, 2026Boiling Water to Make It Safe
When boiling works, when it does not, and how to do it right.
Mar 5, 202607
View all →Testing & Your Water
How to Test Your Drinking Water
Home kits, certified labs, and which to use for which question.
May 30, 2026How to Read Your Water Quality Report (CCR)
Make sense of the annual report your utility is required to send.
May 8, 2026Private Well Water Safety and Testing
Wells are not federally regulated, so testing is on you. Here is how.
Apr 11, 2026What to Do During a Boil-Water Advisory
A clear, step-by-step guide for when your utility issues a notice.
Mar 25, 202608
View all →Regulation & Data
The Safe Drinking Water Act, Explained
The 1974 law behind every US tap, and what it does and does not cover.
Jun 12, 2026How the EPA Sets Drinking Water Standards
MCLs, MCLGs, and how limits and contaminants have changed over time.
May 16, 2026 Clear Tap
Independent, plain-English answers about your drinking water
We do not sell filters or run sponsored reviews. We translate public data and regulation into guidance you can act on.
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