The Arsenic Problem
Arsenic is a naturally occurring element that enters groundwater from rock formations. It's odorless, tasteless, and colorless — making it undetectable without testing. The EPA MCL for arsenic is 10 parts per billion (ppb), but the CDC states no level is completely safe.
Arsenic exists in two forms in water: Arsenic III (arsenite) and Arsenic V (arsenate). Arsenic V is easier to remove. Some systems require pre-oxidation to convert Arsenic III to Arsenic V for effective treatment.
Health Effects: Long-term arsenic exposure increases risk of skin, bladder, and lung cancers; cardiovascular disease; and neurological effects. If your well tests above 10 ppb, treatment is strongly recommended.
Arsenic Removal Technologies
| Technology | As V Removal | As III Removal | Notes |
|---|
| Reverse Osmosis | 95-99% | 40-70% | Best for drinking water point-of-use |
| Activated Alumina | 95% | 20-50% | Requires oxidation pre-treatment for As III |
| Distillation | >99% | >99% | Removes both forms effectively |
| Iron Oxide Media | 95% | 80%+ | AdEdge AdEdge AD26, LayneRT |
| Ion Exchange | 90% | Low | Only effective on As V |
Best Arsenic Removal Systems
| Product | Type | Arsenic Removal | Price |
|---|
| APEC ROES-50 | Under-sink RO | 95-98% As V | $200-250 |
| Home Master TMAFC | Under-sink RO | 95-98% As V | $350-400 |
| Megahome Distiller | Distiller | >99% both forms | $200-250 |
| AdEdge DWS-2S | Point-of-use | 95%+ both forms | $400-600 |
| SpringWell CF1+ | Whole-house | Moderate | $1,200-1,500 |
Critical: Test for Both Arsenic III and V
Standard arsenic tests often only measure total arsenic. For treatment selection, you need to know the speciation:
- If >80% is As V: RO or activated alumina works well
- If >50% is As III: You need pre-oxidization (chlorine, ozone) or a system rated specifically for As III
- Iron oxide media (AdEdge) handles both forms better than alumina
Request "arsenic speciation" from your testing lab. This costs slightly more ($60-100 vs $30-50) but is essential for choosing the right treatment.
Frequently Asked Questions
Does reverse osmosis remove arsenic?Yes, RO removes 95-98% of Arsenic V and 40-70% of Arsenic III. For high As III levels, add pre-oxidation or choose a system rated for both forms.
How do I know if my well has arsenic?Test your water. Arsenic is tasteless, odorless, and colorless. The only way to know is laboratory testing. Test every 3 years if you have a private well in an arsenic-prone region.
What states have the most arsenic in well water?New England (Maine, New Hampshire), the Southwest (Arizona, New Mexico, Nevada), the Upper Midwest (Michigan, Wisconsin), and parts of California, Oregon, and Texas.
Can activated carbon remove arsenic?No. Standard activated carbon has minimal arsenic removal capacity. You need specialized media (activated alumina, iron oxide) or reverse osmosis.
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