Square expansion water tank and FRP septic tank are the new generation of water tank products after FRP water tank. Their products are made of SUS304 stainless steel plate by precision molding, with beautiful appearance, economy and practicality, and durable main body. Compared with other water tanks, square expansion water tanks and FRP septic tanks have many advantages, such as beautiful appearance, light weight, high strength, corrosion resistance, high temperature resistance, clean water quality, seepage prevention, earthquake resistance, never moss, no secondary pollution of water quality, convenient installation, no maintenance, easy cleaning, etc.