Contaminant · Water
Arsenic
What it is
Arsenic is a naturally occurring element that dissolves into groundwater from rock and soil, and can also come from industrial or agricultural sources. It is most common in private wells and in some regional aquifers, and like nitrate it is tasteless and colorless.
Why it matters
The EPA sets a maximum contaminant level of 10 parts per billion for arsenic in public drinking water. That is the regulatory reference point. We score whether a filter is certified to reduce arsenic, not any health outcome. Arsenic exists in two forms (III and V); certified systems are tested for the form they treat.
What removes it
Reverse osmosis (NSF/ANSI 58) is the most common certified route; some systems are certified specifically for arsenic, and certification distinguishes arsenic III from arsenic V. Ordinary carbon filtration does not reliably remove arsenic.
Reference: EPA National Primary Drinking Water Regulations; arsenic MCL 10 ppb.
Scored filters certified for Arsenic
- 7.3Waterdrop G3P800 Tankless RO
A tankless 800 GPD reverse-osmosis system IAPMO-certified to NSF/ANSI 42, 53, 58, 401 and 372 for a broad contaminant list including lead, PFAS, arsenic, nitrate and fluoride.
- 7.2AquaTru Classic Countertop RO
A no-plumbing countertop 4-stage RO purifier certified to NSF standards for lead, PFAS, fluoride and arsenic with an efficient drain ratio.
FAQ
- Will a standard filter remove arsenic?
- Usually not. Most carbon pitchers and faucet filters are not certified for arsenic. Look for a reverse-osmosis system certified to NSF/ANSI 58, and check whether it covers arsenic III, arsenic V, or both.