The water treatment system is a modular-filter based residential reverse osmosis (RO) system that remineralizes the purified water twice to ensure the water is alkaline, but uses only one remineralization filter. The system forces the water to undergo remineralization twice in a modular-filter based residential RO system, using only one remineralization filter. The water produced from the water treatment system is alkaline with a pH of at least 7.5 up to a maximum pH of 8.5. A pH of 8.0 is the mean average.