My local supermarket has bottled water in 2.5 gallon rectangular ptfe containers with a spigot on the bottom, normally about $3 each but occasionally on sale for $1 each, so I have a few of those. I also used to drink bottled water (1 gallon crystal geyser) but have since decided it's a scam. Anyway those 1 gallon bottles are reasonably durable and refillable (pretty sturdy screw top). So I'd drink the bottled water, then refill the empty bottles with tap water and stash them away. I have about 6-8 of those. Plus I usually pick up a 24-bottle case of 0.5l bottles when they go on sale ($3.99 fairly regularly). I keep a case of or so of those in the car and drink them when I get thirsty on the road, and add more when supply gets low. That takes care of rotation all by itself.

An item I rarely see discussed here is marine desalinators. I keep thinking I'd buy one if I hit the lottery. For $2000 or so on ebay you can get a unit that turns 20+ gallons/hour of sea water into fresh water using 12 volt power. Since I live near the ocean that would provide basically unlimited drinking/washing water for a few people as long as there was some fuel available to run a 12 volt generator (e.g. automobile) with.

I'm in an apartment so having a water tank is impractical but if I were in an owned-house-with-yard type of environment, I'd think of installing a 500+ gallon underground cistern. There's a place on ebay that sells those prefabbed (plastic) for a few hundred bucks. It seems very practical, out of sight, fill via garden hose and rotate by pumping some out to water the lawn with a few times a year.