A very strange project. I can see the reasoning to get something familiarly premium from a cheap source, but surely in any developed country your only ever starting point should be tap water. Water that has been bottled months ago and been in (usually plastic) bottles for months can never be better than your local aquifer even if the source is harder. Gets more difficult of course if you are in a big city and your ma…
Personally, I've been tempted to bring water from my parent's house, because their water is loaded with copper, which makes it very hard for ick to spread. Unfortunately, my aquarium is far too large to make it practical to move water from their house to mine.