Water Test Results Centre
How to read an iron result.
Orange stains, metallic taste and what 0.3 mg/L means — plus why iron chemistry on wells is more than one number.
Unit
Usually mg/L (ppm). Labs may report dissolved and total iron separately.
Canadian reference
0.3 mg/L is a common aesthetic objective for iron. It is not a health MAC. Staining often appears around or above that level.
Possible sources
Groundwater contacting iron-bearing rock; iron bacteria; corroding well or plumbing components.
What one result cannot conclude
- Clear water in the bottle can still carry dissolved iron that stains later.
- Iron alone does not explain sulphur odour or black manganese staining.
- A dealer strip is not enough to size oxidation media.
Sensible follow-up testing
- Ask the lab for iron, manganese, pH, hardness, tannins and sulphur if odour is present.
- Note whether staining is orange (often iron) or black/brown (manganese or mixed).
Source correction
Shock chlorination can help if iron bacteria are confirmed, but chemistry treatment is still often required. Do not assume a new well ‘fixes’ iron.
Certification questions
Iron filters are selected for water chemistry and form of iron, not a single NSF health-effect claim. Ask how the installer will verify performance after commissioning.
Treatment options
Air-injection or other oxidation plus filtration is common on Canadian wells. Softeners are a poor primary iron filter when levels are high.
Related guide: orange stains sinks fixtures