Sodium bentonite is a natural clay mineral that swells dramatically when it contacts water, creating an impermeable barrier that stops water seepage through dams and ponds. How Sodium Bentonite Seals Dams When applied to a dam or pond, sodium bentonite absorbs water and expands up to 15 times its dry volume. This expansion fills cracks, fissures and porous areas in the soil, creating a flexible waterproof liner. Application Method 1: Blanket Application The blanket method involves spreading dry bentonite granules evenly across the dam floor and walls at a rate of 1-2kg per m², then covering with 15-30cm of compacted soil. This method is ideal for new dam construction. Application Method 2: Reservoir (Pond in Pond) Method For existing dams, bentonite can be added directly to the water as a slurry or mixed into the top soil layer. The bentonite migrates to problem areas and seals leaks from within. Quantity Calculator Estimate your bentonite requirements: – Small farm dam (0.1 hectare): approximately 200-500kg – Medium farm dam (0.5 hectare): approximately 1,000-2,500kg – Large dam (1 hectare): approximately 2,000-5,000kg Contact us for a detailed site assessment and custom recommendation.