Wouldn't it be easier to just buy a ro filtration setup and build your water up from there? I guess if OP lived in an area that had water usage policies it wouldn't be a solution but otherwise aside from cost I think he's a good candidate for purchasing one. And seeing how time, fuel, and energy are needed to go to the store and acquire ro or spring water eventually it would pay for itself. Why try and chase an ever changing variable when for a few hundred dollars you can eliminate it.
Obviously this wouldn't solve a chloromaine problem but as others have stated campden tablets fix that.