We’ve had very good results with reverse osmosis water for rinsing.
It is audibly superior to everything else we’ve tried.
We’re not saying it’s the best rinse water on the planet; we’re simply saying it’s the best we’ve heard. For a couple hundred bucks, having a reverse osmosis water system installed in your house will turn out to be money well spent if you are cleaning a large collection.
Aquarium stores sell it by the gallon if you don’t plan on cleaning enough records to justify the expense of installing a unit.
Further Reading