A leak prevention drainage system integrated into the base of an aquarium tank is disclosed. The drainage system facilitates transfer of water to or from the interior of the tank, wherein the system comprises three leak prevention mechanisms to redundantly prevent unwanted spillage or leakage from the aquarium during operation. The leak prevention mechanisms include an uppermost stopper having a pull chain accessible from above the water level within the tank, a drain pipe having an internal drain valve for controller flow rate therethrough and a removable end cap at the exit end of the drain pipe. A screen within the drain prevents particulate items from passing therethrough, while a plurality of washers and threaded connections prevent water leakage through the elements of the drainage system. The system is used to controllably drain or fill an aquarium using a hose attachable to the end of the drain pipe.
