When we stopped drinking soda 5 years ago, we wanted to make seltzer water at home. This was before the SodaStream was popular, so I made my own carbonated water maker that connected a co2 tank to a 2 liter bottle.
When we moved back to florida, we never bought another co2 tank, but we dreamed about having club soda on tap. Today we made that dream a reality. We bought a used soda fountain carbonator and installed it under our sink. Now we have unlimited seltzer water whenever we want!