I had great results for many years using tap water, and would still be using it today if not for the poor water quality here at the new house.
Most everyone on the South side gets there water from the City Of East Point. When I was closer to the water treatment plant, I ran a predictable TDS of 57 with very low copper (as stated on the annual report they are required to send out, but I forget the exact number). I did notice after a heavy rain that the TDS jumped a bit, so I always waited a few days afterward to do a water change.
If you need a report, just contact your local water authority and ask them when do they send out the reports, and they might even be able to provide you with a few specifics while you're on the phone, like phosphate or copper levels.
I'd suggest running phosphate media if you use tap water!
I'd still be using tap water if I lived at the old house, but here at the new place, the water quality is bad at best, so bad in fact that after a heavy rain, my son refuses to get in the murky yellow bath water. Hapeville has vowed to fix the problem, and with the recent 33% increase they gave us, they certain have the funds to do so.