Brown Waterfall Water: Tannins from Oak Leaves or Iron Minerals

Two Common Causes

• Tannins: Oak, maple, or other leaves decompose, releasing brown polyphenols. Stains rocks tea-color.
• Iron: Groundwater with dissolved ferrous iron oxidizes to rust-brown on rocks.

Diagnosis

Glass jar test: If water is light brown in a jar but dark in the pond, it's tannins (light absorption). If jar water is also dark, it's dissolved minerals.

Remedies

• Skim leaves promptly; use a leaf net in fall.
• Activated carbon in filter removes tannins.
• Iron: aerate heavily to precipitate, then filter; or use a water softener.

Local Help

Organic Landscaping (914) 921-4858 if in Westchester County, NY.