Originally Posted by Peterf
it would take some time to deplete the 30+ gallon tank. How long would you continue using the same stored fresh water?
Since I live on the Gulf Coast where Hurricane Season replaces Summer and Autumn, I routinely keep my fresh water tank full from June 1st to November 30th each year in case of a hurricane evacuation, with no adverse effects.
Modern fresh water tanks like yours are made of a food-grade plastic that will not leach chemicals into the water to give it a "plastic" taste, though older tanks (before about 1988) predate the "food grade" classification and may (or may not) leach chemicals into the water over time.
As long as the fresh water system was properly sanitized when you de-winterized, and you added clean fresh water from a trusted source, it should not stagnate no matter how long it's in the tank. Stagnation only occurs if there is something biological in the water, which should not be a problem unless oyu get bugs or dead leaves or something into the tank. The worst that would happen otherwise would be the water starting to taste "flat" from depletion of dissolved oxygen over time, but a simple aerator on the faucet fixes that.