How long will bottled tap water remain drinkable?
Assuming you boil it before bottling it in a clean bottle, there’s no reason it couldn’t keep virtually forever.
I don’t know about canned tap water. This site has this to say about canned water.
“The shelf life and the service life of canned water are both indefinite as long as the cans pass the slap test and there are no signs of exterior deterioration.”
“The slap test consists of slapping the can of water against the palm of your hand and listening for a sharp metallic click. This noise is caused by the absence of air to cushion the impact of the water against the can. If this distinct noise is not heard, then air has leaked into the can and it should be replaced.”
“The canned drinking water should be inspected upon issue and every 90 days thereafter, or at intervals to coincide with the inspection schedule of the kit or assembly in which the can is stored. Inspection will consist of the slap test and the shelf life and service life check.”
The site deals with emergency aircraft rations and canned water which is made under a strictly controlled process.
If water is to be stored for long periods, I’d suggest commercial canned water rather than do-it-yourself. I don’t think the commercial bottled water is any good for that purpose. I do remember watching women preserve food by canning. They were always meticulous about how the jars and other utensils were sterilized. Of course, foods have a lot more nutrients for bacteria than does water.