Yep thats all. They are filtering it down to 2.5 microns and blasting it with UV to purify it. If you run an AC system you can do the same thing, even from your car's AC system. Maybe like down here in the high humidity deep south you can get their claimed 20 liters a day.
Have you ever tasted RO water? Go to your local grocer and buy some; it tastes terrible. So, you will either need to filter bacteria, viruses and other crap out of tap, creek or lake water or make RO water and add minerals back for taste and bio-availability. Most people walk around dehydrated as is. Your body cannot absorb the water you feed it because you are deficient, cellularly, in essential minerals. RO water only compounds this problem.
If you are after an emergency-use solution, Katadyn offers a manually-pumped RO water maker.