i want to buy ro but am scared about all the plumbing, is it hard to install? does the ro filters you buy mail-order have instructions and all the parts to install it?
easy peasy if you have a laundry room or extra hook-up (threaded faucet). Most come with installation kits now a days that enable you to connect to a faucet, and a tap to get into your drain (or you can run it where ever you want).
What Gresham said. They usually are available with a variety of fittings, one of which you should be able to adapt for your situation. Installing them can be as easy as screwing the hose bib to your faucet and turning on the cold water.
I bought this unit, and you can see there are a variety of ways to hook it up and parts available.
I have to agree on that. I have mine mounted in the laundry room. The supply hook up is simple. I got a screw on Y on the washer cold water supply. It has two built in valves so I can shut either side off. One side goes to the washer the other side has an adapter to 1/4" tubing that runs to the RO/DI supply. The drain line is shoved down the washer drain.
The correct answer depends on how handy you are. For any reasonable person, it is not hard, but if you have 4 L feet it can be a big charlenge indeed. I don't think I can install it if I have 4 L feet.