Water Test Results Centre
How to read an arsenic result.
The 10 µg/L MAC, regional well risk, and why treatment must follow lab design plus verification.
Unit
Usually µg/L (ppb) or mg/L. 10 µg/L = 0.010 mg/L.
Canadian reference
The Canadian maximum acceptable concentration for arsenic is 10 µg/L.
Possible sources
Natural geology in parts of Atlantic Canada, the Shield and other regions; some mining or industrial history.
What one result cannot conclude
- Taste and clarity do not indicate arsenic.
- A neighbour’s well is not your well.
Sensible follow-up testing
- Resample if the result is close to 10 µg/L.
- Use an alternate drinking and cooking supply while you confirm treatment.
Source correction
You typically cannot remove arsenic from the aquifer. An alternate source or correctly designed treatment is required.
Certification questions
Ask for a model-specific arsenic reduction claim (often NSF/ANSI 58 RO or specialized media). Verify with paired accredited samples.
Treatment options
Point-of-use RO or specialty media sized from the actual influent. Whole-home arsenic systems are specialist designs.
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