If an emergency were to occur, hopefully you would have at least a 3 day supply of water for your family, but if a situation finds you unprepared, there are some resources at home that you can use. One of those is to empty your hot water tank. To use the water in your hot-water tank, be sure the electricity or gas is off, and open the drain at the bottom of the tank. Start the water flowing by turning off the water intake valve at the tank and turning on a hot-water faucet. Refill the tank before turning the gas or electricity back on. If the gas is turned off, a professional will be needed to turn it back on.
Drinking water can also be found in ice cubes, frozen containers of water, or even the toilet tank (not the bowl, of course) provided a chemical disinfectant has not been added to the tank. An important point to remember is to keep water coming into the home shut off to avoid contaminants, until the emergency has passed.
I try to keep extra ice in freezer that might carry me through a short term crisis.