The short answer
Orange streaks on walls, driveways and fences usually come from sprinklers using iron-rich well water. The iron oxidizes and leaves rust behind. Rust won't come off with pressure washing or bleach; it needs a rust remover that dissolves it. To keep stains away, point sprinkler heads away from walls and concrete, or treat the well water to remove the iron.
Where the orange stains come from
According to UF/IFAS Florida-Friendly Landscaping, most Florida well water is high in iron, and iron-rich irrigation water is what causes the orange streaks seen on the sides of buildings. When sprinklers spray that water onto stucco, concrete, fences and curbs, the iron reacts with air and leaves rust behind. Every time the sprinklers run, the stain gets a little darker.
Other causes include rusty metal (like furniture legs or railings) sitting on concrete, and some lawn fertilizers that contain iron.
Why pressure washing doesn't remove rust
Rust is a mineral stain bonded to the surface, not dirt or mildew sitting on top. That's why a pressure washer only fades it slightly, and why bleach, which works so well on mildew, does little to rust. Turning the pressure up to try to force it off just damages the stucco or concrete.
How rust stains are removed
- Identify the surface. Stucco, painted walls, concrete and pavers each need a rust remover that's safe for that material.
- Apply a rust remover. Rust removers are usually acid-based products that dissolve iron oxide. They're applied and left to work for a short time.
- Rinse thoroughly. Once the stain dissolves, the surface is rinsed clean so no residue is left behind.
- Fix the source. Without this step, the stains come right back.
Be careful with DIY rust removers. Acid-based products can etch concrete, discolor paint and harm plants if they're too strong or left on too long. Test a small hidden area first and rinse plants before and after.
How to keep rust stains from coming back
- Adjust sprinkler heads so they water the lawn and beds, not the house, driveway or fence.
- Test your well water. UF/IFAS recommends having it tested first; your county Extension office can help.
- Treat the water. Options UF/IFAS lists include water softeners, oxidizing filters and combined chlorination and filtration systems that remove iron before it reaches your sprinklers.
- Clean new stains early. Fresh stains come off more easily than ones that have built up for years.
Need rust stains gone?
Costa's Pressure Cleaning removes rust and irrigation stains from stucco walls, driveways, sidewalks, curbs and pool decks across Volusia and Flagler counties, for homeowners, HOAs and property managers. Call (386) 679-6569 or text us a photo for a free estimate.
Common questions
Will bleach remove rust stains?
No. Bleach is great on mildew and algae but does little to rust. Rust needs a rust remover that dissolves the iron oxide.
Can rust stains be removed from stucco?
Yes, with a rust remover that's safe for stucco and paint, applied carefully and rinsed thoroughly.