Contaminant · Health
What Arsenic is, where it hides, and what actually removes it.
Mostly a well-water contaminant — and a serious one.
Short answer
Arsenic is naturally occurring and most often reaches the tap through private wells. It has no taste or smell, so testing is the only way to know it is there.
Where it comes from
Private wells in New England, the Great Lakes region, the Southwest, and parts of the South.
- •Naturally occurring minerals in bedrock
- •Agricultural practices and irrigation
- •Historic industry and mining runoff
Last reviewed September 2026
Health context
What Arsenic does to health
Grouped by who is most affected, with the practical steps that follow from it. This is a plain-language summary, not our own testing.
Chronic exposure
Long-term exposure is linked to skin changes, cardiovascular risk and certain cancers. The EPA MCL is 10 ppb.
What to do about it
- •Test annually for arsenic if you are on a well.
- •Point-of-use RO is the low-budget fix.
- •Review state well guidance on depth and geology.
Regulatory source
Read the EPA page for Arsenic →
Certified (NSF/ANSI or WQA listing for the exact model) is not the same as a manufacturer "claims-only" statement on a product page.
Test before you treat
How to actually test for it
DIY strips mislead for many contaminants. Here’s the honest method for finding Arsenic.
Certified lab (EPA 200.8 / ICP-MS)
At-home strips are not reliable for arsenic at the 10 ppb level.
Filter guidance
What actually removes it (and what does not)
Certification matters more than a marketing claim. Here’s the ranking.
RO
Reverse osmosis at point of use is the practical certified option.
Ion exchange
Anion resin works but needs proper regeneration and pH control.
Normalized database
Compare certified options
Same contaminants, same columns, real source links. Blanks mean “not stated” — we don’t invent numbers.
| Product | NSF |
|---|---|
APEC ROES-50 Essence 5-Stage RO RO | NSF 42 — not statedNSF 53 — not statedNSF 58 certifiedNSF 401 — not stated |
iSpring RCC7 5-Stage RO RO | NSF 42 — not statedNSF 53 — not statedNSF 58 certifiedNSF 401 — not stated |
APEC RO-90 Ultimate 90 GPD RO RO | NSF 42 — not statedNSF 53 — not statedNSF 58 certifiedNSF 401 — not stated |
Waterdrop G3P800 Tankless RO RO | NSF 42 certifiedNSF 53 certifiedNSF 58 certifiedNSF 401 — not stated |
Cloud Cloud RO RO | NSF 42 — not statedNSF 53 — not statedNSF 58 certifiedNSF 401 — not stated |
Aquasana SmartFlow Reverse Osmosis RO | NSF 42 certifiedNSF 53 certifiedNSF 58 certifiedNSF 401 certified |
FAQ
Common questions
+Is Arsenic in my tap water?
Only a certified lab test (not a taste test or a strip) answers that reliably.
+Does boiling remove Arsenic?
No. Boiling concentrates most contaminants rather than removing them.
+What's the safest first step?
Test before you treat, then choose a filter type certified for Arsenic.