I have previously installed an RO system that utilized the common tank/bladder reservoir and 3 cartridges under our kitchen sink. The problem is space, you simply do not have a lot of space under this area to install the older style system and if you are like 99% of most other households in America you need this space! I had since removed the system as the cartridges were expensive, hard to get to and replacing them usually created a watery mess.
We eventually had grown tired of purchasing 5 gallons of distilled water per week and finding storage for them in the house. I was considering purchasing a water distillery when I found the Waterdrop G2 system. After I took a close look at it and I figured it was easy enough to install.
Hookup was a piece of cake, they provided you with everything to connect to your exisiting water supply. The hardest part for me was installing power under the sink. I just tapped into the line running to the dishwasher next to the sink for that chore so that involved me having to remove the dishwasher for access. Once I had power available it took about 15 minutes to install the RO system.
The cartridges are fairly inexpensive and very easy to replace. The water tastes great! Some people prefer to add minerals back in for its taste and/or health benefits. We prefer the satisfaction of knowing our water is the puriest available, and any minerals it lacks will be added to our diets through normal consumption of dairy products and of course good ole Gatorade.