If you have lived in St Johns County for more than a summer or two, you have probably seen the orange or brownish-red streaks that appear on driveways and sidewalks — often in patterns that follow where a sprinkler head sprays, or along the edge of a garage approach. Homeowners often assume it is rust from a car, old rebar bleeding through the concrete, or red clay from the soil. In most cases, the real culprit is the irrigation system.
Why Florida irrigation water stains concrete orange.
Northeast Florida's groundwater and well systems — which supply irrigation in communities throughout St Johns, Nocatee, Ponte Vedra, Julington Creek, and much of the surrounding county — contain dissolved iron. That iron is perfectly normal in the water when it's underground, but when it hits air and evaporates on a concrete or paver surface, the iron oxidizes. Oxidized iron is rust. Do that every day across a summer irrigation season, and you end up with progressively deeper orange mineral deposits baked into the surface by the Florida sun.
The pattern usually gives it away: rust stains from irrigation follow the arc of a sprinkler head. You'll see fan-shaped orange markings at the edge of the driveway, on the sidewalk, or on the foundation wall near a spray zone. If the irrigation heads are aimed slightly wrong and hitting the driveway with every cycle, the staining can become heavy in a single season.
Why pressure washing alone does not remove rust stains.
This is one of the most common misunderstandings about driveway cleaning. Standard pressure washing — even at high PSI with a surface cleaner — uses water and mechanical force. That combination works extremely well on mold, mildew, algae, oil, and embedded organic matter. But rust is a mineral deposit, not an organic contaminant. Water and pressure do not dissolve iron oxide. You can pressure wash a rust-stained driveway all day and the orange marks will still be there afterward.
Removing rust from concrete requires a chemical treatment — specifically an acidic rust remover or oxalic acid-based product that reacts with the iron deposits and converts or lifts them from the concrete pores. The process involves applying the rust treatment to the affected areas, allowing dwell time for the reaction to occur, and then rinsing the surface clean. Done correctly, this removes most rust staining significantly. Very old, deeply embedded rust may take multiple treatments or may not fully restore the original concrete color — but the visible orange marks are typically reduced dramatically.
What the treatment process looks like.
- Surface inspection: Identify all rust-affected areas and assess depth of staining. Newer stains respond better than stains that have built up over multiple seasons.
- Pre-rinse: Wet the concrete before applying any treatment chemical to reduce the risk of the product spreading beyond the stained zone.
- Rust treatment application: Apply the rust remover and allow it to dwell per product specifications. The product reacts with the iron deposits and begins to break them down.
- Agitation if needed: For heavier staining, light agitation helps work the product into the pores of the concrete.
- Rinse and evaluate: Rinse thoroughly and assess. Most staining lightens significantly in one treatment. Severe or multi-year buildup may need a second pass.
- Standard driveway cleaning: If the driveway also has mold, mildew, or general grime, the full pressure wash with surface cleaner follows the rust treatment.
How to prevent rust stains from coming back.
Treating the stain fixes what is already there, but the same irrigation system will redeposit iron on the surface the moment it starts running again. The long-term solution is to adjust the irrigation heads so they are not directly hitting concrete or paver surfaces. Most irrigation heads can be rotated or have their arc adjusted — a small change to the spray direction is often all it takes. If the iron content in the water is particularly high, a whole-irrigation iron filter is another option, though that is typically a separate contractor discussion.
For homeowners who have the irrigation situation under control but want to protect the cleaned surface going forward, sealing the concrete is an option. Sealed concrete is less porous and resists iron deposit penetration better than unsealed concrete, which makes future rust staining easier to rinse away before it sets. Paver driveways can also be sealed — see the paver sealing page for what that process covers.
Common areas in St Johns County where rust staining shows up.
Rust staining from irrigation is particularly common in communities where homes use well-sourced irrigation rather than reclaimed water systems. Julington Creek, Fruit Cove, older parts of Ponte Vedra, and sections of St Johns with private well irrigation see this regularly. Newer Nocatee homes with reclaimed irrigation water tend to have less iron-related staining, though they are not immune — rust can also come from metal objects left on concrete (patio furniture, tools, plant pots with metal drainage rings) that corrode and transfer iron to the surface below.
If your driveway, sidewalk, or patio has orange or brown staining that has not responded to previous cleaning attempts, send a photo and Kolby can confirm whether it is rust and what the treatment plan looks like for your specific surface and staining depth.