I would have to say it all depends on your water supply.
I generally use spring water without issue for a number of reasons. A few years back I was getting an annoying but not beer ruining infection and pretty well narrowed it down to the use of hot tap water to rinse and start siphons. I still use some tap from time to time, but only in full boils, or pre-boiled.
The local water source is the muddy Mississippi, and while perfectly safe to drink the quality (taste, mineral content, chlorine content, etc.) can vary widely during the year. Also, in summer the stuff comes out near 80 degrees, which is perfect for yeast as well as every other beer spoiling organism. The local water system is nearly 100 years old, and it is not uncommon to find sand in your faucet screen.
As to freezing the jugs, if you time it until it just begins to freeze (usually a ice crust forms on the inside of the jug) you can easily get the benefit of nearly frozen water (32 to 33 degrees) without the chunk of ice to deal with.