the cylinder block is made of environmentally friendly and high-quality stainless steel material, which is durable, not easy to wear, and easy to operate, providing an economical and high-performance configuration. In the whole working process, the multi-function valve (six positions) is used to control to achieve different functions. after normal backwashing (discharge the dirt accumulated in the filter), after backwashing, the remaining dirt in the water pipe is discharged, and the drainage is not filtered, circulated and closed without filtering.