What are tannin stains?

Tannin stains are brown or rust-colored discoloration that appears on decks, concrete, siding, and other exterior surfaces in areas with high moisture and organic debris. These stains form when tannins, natural compounds found in wood and leaves, dissolve in water and leach onto adjacent surfaces. Rain, humidity, and proximity to trees make the Myrtle Beach area particularly prone to tannin runoff.

The stains typically appear as streaks or patches below roof gutters, along deck edges, or surrounding leaf litter. While tannins themselves are harmless plant compounds, they can make surfaces appear aged and neglected. Tannin stains differ from mold, algae, or mildew, though these contaminants often appear alongside tannin discoloration.

Left untreated, tannin stains can become more stubborn over time as they bond to the surface. They respond well to pressure washing when treated promptly, particularly on concrete and composite decking. Wooden decks require careful pressure settings to avoid damage while removing the discoloration. Pressure washing professionals in the area understand the specific stain types and surface vulnerabilities common to coastal South Carolina properties.