Depending on the type you are considering, it may be able to have it installed in a location where it could filter the water for both. I was concerned that there would not be enough room under the sink for everything and the person I consulted said he could install it in the basement and pipe it so I could get RO water either at the sink or at the fridge.

I called a local company that only deals with filtration systems. We have a well and had used them to install our UV system a couple of years ago. They came out, tested my water, made recommendations for filtration based on that test, and allowed me the chance to talk all of this through. You might look into whether something similar is available in your area.

In my last 2 homes I put the RO under the sink with a dedicated faucet and also had a line to the fridge which fed the icemaker and water dispenser.

Oddly enough, in my current house the RO is under the main sink, but the dedicated spigot is at the prep sink. I just realized that it makes no sense and I have no recollection of why I did it that way.

There is no reason other than available space that precludes putting an RO system in a remote location and plumbing it to wherever you need the water. By system I mean carbon prefilters (essential if there is chlorine or chloramine in the water, or any silt), RO membrane filter, nominal post carbon filter, and storage tank, at a minimum. More complex setups are often used. See Spectrapure's website among many others for examples.

The plumbing over longer distances is most easily done with 3/8th-inch food grade polyethylene tubing, connected with John Guest type fittings. Portage Specialties, among many sources, has tubing and this type of fitting for sale. Just cut the tubing to length and push to connect.

My RO system is plumbed to feed a centrifugal humidifier, a future family room counter area, a plant watering wand, two kitchen sinks and a refrigerator icemaker

RO filtering can leave water slightly acidic, which promotes corrosion of some faucets. This depends on the nature of the water being filtered. I recently determined that my RO water is still alkaline after filtering alkaline pre-treated municipal type water, so I don't have a problem of that sort. If acidic, then another "filter" is needed on the exit end of the RO system that contains limestone chips to neutralize the water. Simple RO systems avoid all this by using plastic and stainless steel faucet parts.

The approach I recommend is determine what you want the RO water for and how much you will use, peak and average. Then find a system that will accommodate those requirements.

kas

My reverse osmosis filter (multiple filters and tank) is under my main kitchen sink. I have a spigot on the main kitchen sink. I recently installed a new fridge with in the door water and ice and I plumbed a small line under the kitchen floor (ceiling of basement room below the kitchen is unfinished) to the wall behind the fridge and then to the fridge. I don't even use the Brita filter in the fridge. The amount of filtration done by the reverse osmosis is so much better than anything a Brita filter could ever do. And this way I can have tepid or cool water for drinking and cooking, and even filtered ice cubes.

Ours is in the basement with lines running to a tap at the main sink and the fridge.

Ditto jdew...mounted in the basement, with lines running up to a spigot
at the sink, and to the fridge.

My ideal situation would be fridge or a combo sink and fridge (like Pricklypearcactus), but they are on opposite ends of room. My concern is copper pipes, and leaching of copper from the acidity (is what I've read). We are renovating kitchen, right now GC has a separate copper water line running to back of where fridge is supposed to be. Should I just bypass the copper pipes and use that food grade polyethylene tubing. Are there problems with that tube leaking if you go for a distance (maybe 14 ft)?

thanks

The guys that have installed my RO systems have always run plastic tubing through the pre-plumbed copper line.

Protecting the poly tubing with a copper line has merit wherever there is risk of damage. I've had my poly tubing mounted in various areas for several years without any evidence of degradation or leakage.

I suspect regular food grade polyethylene is more resistant to UV than, say, PEX, but I wouldn't deliberately run it exposed outside in the sun or up close to the output of a fluorescent lamp. I just recalled that an exposed end of a previous project's poly line is outside partially under my deck, and I just examined it (best I could in the rain) and it looks uncrazed by its partial UV exposure.

Use John Guest type fittings and you should be fine for a lifetime of good water.

kas

Ok, I'm not really sure what I'm talking about with plumbing, but here goes my best explanation for what we have...

The RO tank is under the main sink with the faucet for it also at the main sink.

We don't have an ice maker/water dispenser in our main fridge, but we do have an ice maker in our bar fridge on the other side of the room. Our plumber ran tubing from the RO to the bar fridge for the ice maker and we also had some kind of on-demand pump installed to make sure the psi is high enough for the ice maker requirements.