The PENTAIR Reverse Osmosis Drinking Water System Filter Replacement Membrane is a 4-stage system. These 4-stages include a 20-micron sediment pre-filter, a granular activated carbon (GAC) pre-filter, reverse osmosis membrane and a granular activated carbon post-filter. The membrane design reduces the amount of water down the drain so it fills up the reserve tank quicker. For best results replace every 18 months.
- Membrane design reduces water loss by up to 50% 
- Replacement is quick and easy with 4-stages built into 1 filter and no tools required 
- Unit is long-lasting, no replacement for up to 18-months 
- Quickly fill reserve tank, up to 50 gallon per day 
- Easy to change with no tools required 
- 18-month filter life 
- Filter life in gallons is a approximate amount, due to variables in water quality