Simplify a reverse osmosis by removing the membrane. now you have a dual purifier. Water that is more Zephyrhills or Evian and less Aquafina or Dasani. If you like minerals in your water like zinc and magnesium then a dual purifier is the way to go; two filters which only remove sediment and gases. There is no storage tank and water is produced 1 gallon for 1 gallon.
The cost of this system is $150.00 and includes installation. It has a 5 year warranty on all nonperishable parts.