We purchased an 8' length of white food quality hose to tap our water heater if we ever needed to, as the spigot is only two inches from the floor. The shut-off valve to the outside water supply is nearby, so in an emergency we can shut it off, open the sink valve in the second floor bathroom, and gravity feed all of the water in the pipes through the water heater valve. We also use four 7 gallon 'jerry can' food quality plastic totes to store water. We rotate that water yearly in the fall when we freeze-proof the outside sillcocks. We store a gallon of emergency clorine bleach in our cache, and rotate it out when the one in the laundry area is empty, replacing the bottle in the cache.