WAHA is a funnel-shaped, biodegradable module made from straw and algae biopolymers for use in arid environments and rural communities. It passively captures and directs rainwater to plant roots while shading the soil to reduce evaporation, solving the need for active irrigation. The module decomposes over 1–2 years, enriching the soil with nutrients, leaving no waste, and supporting land regeneration and biodiversity.