Dont get anything smaller than a 75GPD model. I have a 100GPD model and I can fill a 30gal trashcan in a 6-7 hours.
The space it takes up is next to nothing. when you compair the space your buckets take that you use to transport your water. I have two 30 gal
trashcans. one for fresh RO
water and one to mix saltwater in. My RO
unit sits on a shelf next to these trashcans or you could mount it on the wall. YOu can also use the RO
and waste water for other things so it not as wasteful as you would first think.
How much water do you buy a month? If you had the ability to make water on yourown would you do more water changes? I always look at the RO
unit as an investment vs an expense.