It is essential that every person have enough and it be safe to drink.
Needs differ according to age, physical condition, activity and environment.
This does not include water for cooking, bathing or pet allowances. Assuming clean and deodorized food-grade containers are used, untreated water straight from your tap should keep 6 months, but MUST be changed thereafter. Bacteria-free water, which means successful treatment by one of the accepted methods listed, will keep several years depending on heat, light, degradation of the container, etc. Store your water away from paint and petroleum-based products, acids or anything releasing objectionable odors like fertilizer or household cleaners. While able to hold water, these lower grade containers are permeable to certain gases.