You're probably right if the city of Tracy treated their water with chorine, but they treat their water with chloramines which does not off gas like chlorine does. Not treating the incoming drip would eventually lead to elevated chlormine levels that could get to lethal levels pretty quickly.
I also saw that the tank is back up for sale the other day:
http://sfbay.craigslist.org/nby/for/4152745392.html
Man, the stand looks flimsy. It almost looks like the stand was made to just to move the empty tank acound since it's on wheels.
OP, if you are still thinking about getting this, you would need a new stand.