A mobile water reservoir made of double-layer composite PVC, foldable and rollable, featuring a ring of floats at the top; after filling witer, the tank automatically forms its shape as the water level rises, presenting an onion-like appearance. The bottom is equipped with valves and hose couplings for quick connection to fire hoses for filling nd draining. The tank bottom can be fitted with a puncture-resistant liner according to usage requirements, making it suitable for field environments. It can store various liquids such as watil, and acid-base solutions. Primarily used for firefighting, it is categorized into water bags, water storage pools, and reservoirs. Placed in advantageous positions within forest areait serves as a water source carrier for water-based firefighting equipment when forest fires occur;