How long to keep potable water in holding tank

Full-timers don't have the option of filling at home. We full-timed 16 years and boondocked in the boonies the majority of time or used public park campgrounds. We never sanitized our tank. We got our water from all kinds of sources. We had a good filter from RV Filter Store online for our incoming water and a filter at the kitchen sink for taste. The water we drank and cooked with came from our water tank. We didn't buy water. No issues.