Martin, just wanted to throw my 2 bits in, they do sell kits to use on your generators that you can use propane or natural gas with your generators in a loss of power situation. I thought going to that during our long hurricane outages, but the amount of propane my generator consumes, price and availability led me to stick with gas. During those times in my area, gas was the only thing available, no kerosene, propane or natural gas was available at my location but every location is different. If you can get propane in that area that's great, better yet kerosene would help out as well. We were raised up utilizing kerosene as back up for heat and cooking in the old days and we survived and sometimes that old tried and true thing sticks around. As for water we always lived near a alternate water source weather it be creeks, lake, ocean or lots of swimming pools. If those were unavailable I would start buying a lot of food grade 55 gallon drums for back up and keep them filled all the time and rotate them out when needed. Like you said with a big communality, you could look into bladders as well. A underground Water Bladder with pumps and solar/wind source for backup would be ideal, you need to keep that water from freezing and the beauty about underground is it holds temps above freezing better.

http://uscarb.com/04451-kits.htm

http://www.interstateproducts.com/water_bladders.htm

http://www.usplastic.com/catalog/default.aspx?catid=459&parentcatid=458