I change them out at the end of each year and use them to water plants. I'm very sure I'll not mind the plastic taste in an emergency situation :)

The datrex drinking water is rated for 5 years, and it tastes the same — like distilled water — 1 or 5 years in. It's nice to actually be want to drink it in a non-emergency situation if you just need some water.

Dunno why is this downvoted -- put an emergency plastic water bottle in your car during summer season and let me know if you would be able to drink the resulting mush, even in an emergency.