In 25 years of motorhoming, I have never had a problem with water contamination, thanks to U.S. federal and local drinking water regulations.
I have had problems with extremely hard water,i.e. Quartzsite water, which I have solved with a portable water softner http://www.campingworld.com/shopping/item/portable-wate...ner-conditioner/6848
and the installations of a reverse osmosis unit (Watts brand) that feeds a drinking water faucet in the kitchen and bathroom and soon the icemaker.
I would suspect that an Ozone system would require 110V, so it would only run when you are plugged in at a site with full hook ups. The water there should not have anything in it that would require purification. If it did, I would call the local health department.