I'll get kicked for this but not all water is unsuitable for a FOWLR tank. Get a report from your water company that will show whats in it. Test it for nitrate, phosphate, and silicates, be sure it is well mixed and aerated for at least a day, and it may be fine.RO/DI is great; but there are a whole lot of FOWLR tanks running on tap water. Before moving after Katrina, I didn't have RO/DI and kept a lot of fish for many years on tap water, in my two previous residences. I used tap where I live now for about 3 years with no problem and just converted to RO/DI because I was setting up a large reef. Tap water isn't all good, but it isn't all bad either; it depends on your local water supply and what you want to keep. This hobby is expensive; but a modest FOWLR does not always require RO/DI water. $500 worth of LR , top-shelf lighting or a skimmer. All of this stuff will come in time for the hobbyist who is serious; but getting into the hobby doesn't require a 2nd mortgage. Use common sense, hardy fish, good WC habits, good nutrition, QT everything and , in many/most areas, you'll be fine. BTW; prior to Katrina, I had many long-lived fish in tap water; including 2 moorish idols, an achilles tang, regal angel, and a PB tang---all for at least 10 years. Also, if your friend is in Knoxville, I have a good friend with a great 180 gal FOWLR, using Knoxville tap water.