Umiya Gold Water Tanks are 5-layer water tanks made of food-grade virgin plastic, which is safe and durable. These tanks are designed with a unique 5-layer protection system that includes an inner layer of food-grade polyethylene, an outer layer of anti-UV treated polyethylene, and a middle core of thermocol insulation. This helps provide excellent UV protection, thermal insulation, and resistance to corrosion. These tanks are also designed with a unique interlocking system that prevents any leakage from the tank. Additionally, the tanks come with a 10-year warranty, so you can be sure that your investment will last for years to come.