I haven't tested the TDS, but I've heard people say around 35ish...at least in the city. We live outside the city, so it could be different. No copper pipes in this house, it's all CPVC.
I'd prefer not to use it, but we still don't have an RO and buying water at the grocery store got old quick. The algae from using tap isn't really THAT bad at all. Heck, my acro loves the water, it's thriving.