I agree stainless steel and glass are best. Keep in mind plastic will leach chemicals from the ground if the container sets directly on the ground especially concrete though if temps are below 77 than the plastic won't react to the heat and safe to store on the ground including concrete, not an issue here but can be an issue in the South, but if the the plastic containers (blue BPA free) are set in a dry cool place off the ground with no direct sun light then the plastic are safe. Most plastic pop bottles and milk jugs are totally safe for a limited time but will easily last 6 months except for the milk jugs, milk jugs will last 90 days if kept refrigerated, I personally would refrain from using milk jugs.
Also keep in mind, most canned goods are lined on the inside that also leaches if above 77deg F
So while the focus have been placed on plastic water containers/bottles for some reason canned goods are ignored.
Also here's a link to other information regarding plastics; The Murky Truth About Leaching Plastic Bottles
http://www.livescience.com/5487-murky-truth-leaching-plastic-bottles.html