Regnvand

Regnvand, or rainwater, is water that originates from precipitation and can be captured for storage and later use. In urban and rural settings it is commonly collected from roof surfaces and other paved or impermeable areas, then directed into tanks, cisterns, or infiltration systems. The quality of regnvand depends on the catchment surface and any filtration or treatment that is applied.

Collection and treatment methods vary. Typical systems include gutters and downspouts, leaf guards, first-flush diverters to discard the initial dirty water, and storage tanks or underground reservoirs. Filtration and disinfection can be added, especially if the water is intended for human contact. For drinking or cooking, regnvand generally requires more intensive treatment to meet drinking-water standards and is often subject to local regulations.

Common uses are non-potable and include irrigation, landscape washing, toilet flushing, car washing, and cooling processes. With appropriate treatment, regnvand can be used for potable applications, but this requires strict purification, regular testing, and compliance with drinking-water regulations. Using rainwater for non-potable purposes typically reduces demand on municipal water supplies and can lower utility costs, while also reducing stormwater runoff and local flooding.

Challenges and considerations include variability in rainfall, potential contamination from roof materials, bird droppings, debris, and algae in storage tanks. System maintenance, backflow protection, and zoning or building-code requirements are important. Design choices consider catchment surface, storage size, tank materials, and the intended uses of the water.