Tap water through the precision cartridge and activated carbon cartridge pretreatment, filtration of sediment and other particles and adsorption of odors, etc., so that the tap water to become cleaner, and then through the reverse osmosis device for water purification and desalination, the purified water into the storage tank to store up, the water quality can reach the national standards for tertiary water, and at the same time, reverse osmosis device to produce water waste water discharged. The water quality can reach the national third grade water standard, at the same time, the wastewater from the reverse osmosis device is discharged. Reverse osmosis purified water through the purification column for deep desalination treatment to get a water or ultrapure water, and finally if the user has special requirements, it is in the ultrapure water behind the ultraviolet sterilization or microfiltration, ultrafiltration and other devices, to remove the residual bacteria in the water, particles, heat and so on. Precision cartridge, activated carbon cartridge, reverse osmosis membrane, purification column are materials with relative life, precision cartridge and activated carbon cartridge is actually the protection of the reverse osmosis membrane, if they fail, then the reverse osmosis membrane load on the increase, the life is shortened, if you continue to turn on the words, then the quality of the pure water produced by the water quality will decline, and then increased the burden of the purification column, then the purification column of the life will be shortened. The end result is to increase the cost of ultra-pure water machine.