What is the purpose of first-flush diverters in rainwater harvesting?

• A. To filter water after storage.
• B. To pump water from the tank.
• C. To divert the initial dirty runoff away from the storage tank.
• D. To heat water.

Answer: (C)

In rainwater harvesting, the first-flush diverter serves to protect the tank by handling the initial, dirtier portion of the runoff. When a rain begins, the roof carries a buildup of dust, leaves, bird droppings, pollen, and other grime that accumulated during dry periods. The diverter redirects this first burst of water away from the storage tank, so the water entering the tank is cleaner for the rest of the rain event. By preventing the dirtiest portion from entering, it reduces sediment buildup, minimizes clogging of filters and outlets, and helps improve water quality and system longevity. Filtering after storage would still require additional equipment and wouldn’t prevent dirty water from entering the tank in the first place, pumping is a separate function, and heating water isn’t related to this purpose.