AJ asked me:
On ProvidentLiving.org, they say that chlorinated municipal water doesn't need any further treatment.
For me, I hide clean juice bottles filled with water behind a lot of my furniture. I keep a mental note of the last room to which I added water, and if I had to drink it I would drink the freshest water first.
I try to empty out a whole room of bottles at a time onto my garden, and then replace it. But I'm not perfect at doing that.
I have three 50 gallon water barrels in my garage, and I try to refill them every six months. I have read that opaque barrels are better for keeping out light (light would allow bacteria or algae to grow.) My garage doesn't have any windows, so that helps too.
With older water, I will use a backpacker's water filter on the water before drinking it.
But from experience, I know that the majority of the water will be used for washing, so only a small amount of it will ultimately need to be filtered for drinking.