Recapping:

Aerate to get rid of chlorine & stale taste, also recommended to improve taste of boiled water. Store in a cool dark space. Rotate stock. Shelf life from 1 to 3 years (varying opinions).

My work consists of installing municipal water pipes. When tested our water must show 0 bacteria. So, in theory, you could store city water indefinitely in sterile & airtight containers as it has no bacteria to reproduce and make you sick.