Water Test Results Centre
How to read a lead result.
First-draw vs flushed samples, older plumbing, and certified lead-reduction filters in Canada.
Unit
Usually µg/L (ppb). 1 mg/L = 1,000 µg/L.
Canadian reference
Health Canada’s maximum acceptable concentration for lead is 5 µg/L. Sampling method (first draw vs flushed) changes what the number means.
Possible sources
Lead service lines, solder, brass fittings, and some older plumbing — not usually the treatment plant finished water.
What one result cannot conclude
- A flushed sample can miss first-draw lead at the tap.
- The municipal plant report is not your kitchen tap.
Sensible follow-up testing
- Follow the lab or city’s sampling protocol for first-draw lead.
- Check local lead-service-line maps where they exist (for example Toronto and Montréal).
Source correction
Service-line replacement is the lasting fix when the line is lead. Point-of-use treatment can reduce exposure at a tap while that work proceeds.
Certification questions
Look for the exact lead-reduction claim on NSF/ANSI 53 (filters) or 58 (RO). A standard number without the lead claim is not enough.
Treatment options
Certified point-of-use filters or RO at the drinking tap. Whole-home lead treatment is uncommon and must be designed carefully.
Related guide: lead testing drinking water