Hidden Water Sources

I have copied the below from the FEMA (Federeal Emergency Management Agency) website:

HIDDEN WATER SOURCES IN YOUR HOME
Safe water sources in your home include the water in your hot- water tank, pipes, and ice cubes. You should not use water from toilet flush tanks or bowls, radiators, waterbeds, or swimming pools/spas.
You will need to protect the water sources already in your home from contamination if you hear reports of broken water or sewage lines, or if local officials advise you of a problem. To shut off incoming water, locate the main valve and turn it to the closed position. Be sure you and other family members know beforehand how to perform this important procedure.
To use the water in your pipes, let air into the plumbing by turning on the faucet in your home at the highest level. A small amount of water will trickle out. Then obtain water from the lowest faucet in the home.
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.
EMERGENCY OUTDOOR WATER SOURCES
If you need to find water outside your home, you can use these sources. Be sure to treat the water according to the instructions on the next page before drinking it.
 Rainwater
 Streams, rivers, and other moving bodies of water
 Ponds and lakes
 Natural springs
Avoid water with floating material, an odor, or dark color.
You should not drink flood water.