piperjim
They do make portable reverse osmosis systems. But the way they work is still the same. They will waist at least 3 times more water than you get from the system. That is, if you fill a 20 gallon reservoir with RO water, at least 60 gallons went down the drain. That is in a nutshell why I went with a custom built water filtration system. On a small scale RO is fine, but on a larger scale it defeats one of the reasons for growing hydroponically. That is using one tenth the water to grow the same amount of plants. You cant really make that claim when you dump three times the water used by the system/plants straight down the drain.
I don't know your water quality, and that's the first thing to figure out. But municipal water is generally treated for human consumption. That isn't to say it will be fine for your hydroponic plants. Especially when I cant say/know how it's treated. I also don't know if you have a water softener system, or per-filters in your water lines.
But here are a couple of articles on the importance of water quality:
Hydroponic H2O: Water Quality and Treatment
Water Wisdom For Hydroponics