Hi j_chicago.
The only obvious aspect is the little faucet mounted in the sink deck.
Hence the first question is; does your existing kitchen sink have a spare hole in the back? I was lucky mine did, in fact it had three!!
One is a problematic soap dispenser. One is the RO dispenser we all drink from and use for all cooking. I put another mini faucet in the third hole. It's my RO waste water.
My tap water is about 150ppm Total Dissolved Solids (TDS). That water runs thru the pre-filters and the carbon block to strip the membrane clogging particles, and the membrane frying chlorine, and human frying fluoride. So the waste water from the RO process is still pretty dang clean coming in at about 40ppm. This runs into my sink instead of the usual straight to the sewer. This allows us to catch the water in a bucket for plant watering washing etc. The RO water tilts my TDS meter at zero. I don't bother with DI. I make up 1 to 2 gals a day for about 8 months before I do a water change in my tank. If that RO filter wasn't working just right, I would not make those change periods without serious salinity shifts showing up.
Next if your sink doesn't have a blank hole, does it have a soap dispenser? You can yank the soap dispenser and use it for the mini-faucet. Then just use a pump soap dispenser that sits on the counter. They are often easier to maintain, and fill, then the in-sink ones anyway.
I can't adequately stress how important consistent "water making" is to having a trouble free, low maintenance RO/DI system.
And if you ever thought about the cr@p found in city water systems you'd want some sort of filter anyway.
Example: Our city has a reservoir. They get algae blooms. What do they do about the blooms? They dump in copper sulfate!!! A deadly poison to people... This kills the algae. Then they heavily chlorinate the resulting water. Organics(dead algae) mixed with chlorine generates chloramides a potent human carcinogen...
Need I say more? You want a filter.
