The 4 stage Ro/Di is pretty basic and will fit easily under the sink and works well for most. The is two ways you can hook it up you can go the basic route. They make a fitting that hook up to you faucet and that fitting connect to the red line, put the black line in the sink drain to drain your waste water, the blue in a bucket for you filtered water. Or the cleaner looking route a T fitting that fits your cold water supply line under the sink and will T off to the red line( the red line should have a shutoff valve too so you can shut the water off when not in use) , A drain saddle clamp to clamp to you drain line and then your waste water line the black line well connect to it, and then blue line again is for you filtered water into a bucket or what ever you going to use to fill. There both pretty simple to hook up.