The present invention relates to a multi-purpose water tank, and more specifically to a multi-purpose water tank, which enables water accommodated in the water tank and a liquid chemical to be effectively agitated when the liquid chemical is mixed with the water, which can prevent an agitated liquid discharged from the water tank from including impurities, thereby preventing an obstruction phenomenon when a sprinkler and a high-pressure spray nozzle are used, which enables a filtering rod installed inside the water tank and configured to filter out impurities to be separated, thereby facilitating the maintenance and repair of the filtering rod, and which enables impurities accumulated inside the water tank to be effectively discharged along with a small amount of water, thereby enabling the clean state of the water tank to be maintained.