Orange stains from well water: iron, and how to fix it
Iron isn't a health risk at well water levels. Above 0.3 mg/L it causes orange stains, a metallic taste and sometimes slimy iron bacteria. Treatment is about comfort, not safety.
- US (EPA)
- 0.3 mg/L, a cosmetic guideline.
- Ontario
- 0.3 mg/L aesthetic objective.
What it is
Iron dissolves from rock as groundwater moves through it. Water can look clear from the tap and turn orange as iron meets air. Iron bacteria can feed on it and leave a reddish slime in toilet tanks.
What your number means
- Within limitsBelow 0.3 mg/L
No staining expected.
- Worth a look0.3 to 1 mg/L
Stains and taste. Treatment is optional.
- Worth a lookAbove 1 mg/L
Heavy staining likely. An iron filter usually pays for itself in fixtures and laundry.
What to do
- Decide whether stains or taste bother you enough to treat. There's no health need.
- Ask about an iron filter, or a softener rated for your iron level.
- If you see red slime, ask about iron bacteria and shock chlorination.
- Test manganese too; they often come together.
How often to test
With a full panel every 3 to 5 years.
Common questions
What causes orange stains from well water?
Almost always iron. Above about 0.3 mg/L, dissolved iron turns to rust when it meets air and leaves orange or reddish brown stains on sinks, toilets, tubs and laundry. A water test for iron confirms it, and an iron filter usually fixes it.
Is iron in well water bad for you?
No. Iron in water isn't a health concern at these levels. The issues are stains, taste and clogged fixtures.
Why is my water clear but turns orange?
Dissolved iron is invisible until it reacts with air and becomes rust colored particles.
Sources: EPA secondary standards; Ontario: testing and treating private wells. Limits checked October 2026.