go to www.MajorSurplusNSurvival.com They explain what is needed, and you have an indication of products and prices.I am not affiliated with MSS! They are the nearest dealer and I am most familiar with their offerings. Aside from antibacterial agents ( clorine, iodine etc.), you will need an oxygenator to inhibit algae. If this is an urban setting, what is your potential disaster,flooding, earthquakes,fire? After the Northridge quake, bottled water ,while rationed was readilly resupplied. It might be different if the transportation network ( flooding) is down.