So half a year they have to get it from north or preserve in sterile tanks? :) I live near Urals above 99% of Canadians and there is no snow for 6 months.
An example, San Francisco historically got it's water from the Hetch Hetchy Reservoir. It's all from alpine snow melt and springs. Used to not be chlorinated because it's organic content is very low. I assume a lot of Canada is the same.
There is more precipitation during a warmer half of the year on their territory outside of ocean shores where it's in reverse, also the gap between those grows further to north.