We invented a reverse osmosis system that will fit almost any under sink cabinet. Aquaphor RO-101 is the most compact reverse osmosis water purifier with the full-size membrane. You’d be surprised how little space it requires.
However, compactness does not lead to diminished performance - RO-101 replacement filters contain 10% more adsorbents than traditional 10'' cartridges for drinking water systems and a full-size 50 gallon per day membrane. It means that you have fresh homemade drinking water from tap whenever you'll need it.