Reverse osmosis drinking water treatment system with backwashable precise prefilter unit

A reverse osmosis drinking water treatment system with a backwashable precise prefilter unit, comprising:

• a super precise filter,
• a pressure pump for moving water in the system, wherein the pressure pump includes an automatic control system,
• a reverse osmosis membrane or a nano-filtration membrane operatively connected with an outlet of the super precise filter such that water passes through the super precise filter and then through the membrane,
• a pressure tank to maintain the system under pressure,
• a post filter operatively connected with an outlet of the membrane such that water passes through the membrane and then through the post filter,
• a drinking water dispensing apparatus operatively connected with an outlet of the post filter such that water passes through the post filter and then to the drinking water dispensing apparatus, and
• an independent backwasbable precise prefilter unit, operatively connected with an inlet of the super precise filter, wherein said backwashable precise prefilter unit contains a backwashable prefilter column installation and a transfer valve,
• wherein said backwashable prefilter column installation includes three filter columns in series, wherein each column is separately packed with long life and recoverable filter materials, and
• said transfer valve includes a five channel ball valve, wherein the five channel ball valve is switchable between the following working positions:
• a cleaning water position, a discharging water position, and a backwashing position.