Getting Water From Your Water Heater During An Emergency

How To Get Emergency Water From A Water Heater
http://www.wikihow.com/Get-Emergency-Drinking-Water-from-a-Water-Heater
A typical home water heater can provide between 30 and 60 or more gallons of clean drinking water during a disaster. Hurricanes, floods, earthquakes, and other power outages may prevent you from having many things, but clean drinking water is not one of them.
1. Turn off the electricity or gas to the water heater. You will be draining the clean drinking water from it. If there is power to the tank while it's empty, damage to it will be certain. Turn off the circuit breaker for electric types or close the gas valve for natural gas and propane types. Most electric water heaters in residential applications are 208 / 240 volts, and supplied by a double-pole circuit breaker or two fuses rated at 30 amps.
2. Preserve the cleanliness of the water in the tank by closing the supply valve to the tank. When water service is restored, the water department will be pumping water that could be contaminated. This will be fine to use for flushing toilets and for cooking, but not for drinking. See the Tips below for information on determining which one is the supply valve.
3. Find the valve at the bottom of the tank for draining when it needs servicing. This is where your clean drinking water will come from. Many water heater valves have a connector for hooking up a garden hose to the drain valve. A short 3 foot length of garden hose will make the collection of the water easier. A washing machine's supply hose is the perfect length and is available in many homes. Connect the hose and open the valve briefly to flush any debris that may have collected in the valve. Make sure the drain, hose, and container are clean before using them.
4. In order for the water to be drained from the tank you must allow air to get into it. This is easy to do by opening any hot water tap in the building such as the kitchen or bathroom sink.
5. Wait for the water to cool down, then purify it. Water heaters are notorious for trapping sediments. The "heavier than water" sediment sinks to and collects at the bottom of the tank because hot water is drawn from the top of the tank, rather than the bottom. Purification filters will not work on hot water, so let it cool down!.
Many people mistakenly believe that the tank is made of glass (or another inert substance). It is not. The inside of the tank will likely be lined with glass to prevent corrosion, since corrosion is the leading cause of water heater failure. There is no danger cooking or consuming water that has been contained in a water heater.
Before disaster hits, mark which valve is for the water supply. Run some hot water from any sink. Go back to the hot water tank and feel the two pipes attached to it. The supply line will be the colder one. Somehow mark the valve as "supply". This will be the one to close in an emergency so that contaminated water will not go into the tank as you drain the clean drinking water that is stored in it.
It is a good idea to flush some water from the bottom of the tank once or twice a year. Sediment can collect on the bottom of the tank. Draining some water under pressure will clean out the sediment.
Turn off the power supply to the tank first. Even if there is a power failure you must unplug, turn off the circuit breaker, or close the gas valve first.
Allow the tank to fill before restoring power to the water heater. Open the supply valve and wait for the water to run out of the open hot water faucet.
Be sure that the water has had time to cool before opening any valves on the water heater!
Be sure the water inside the water heater is not soft water. It can contain excess sodium (the harder your water supply is, the more sodium is used to soften it), which is not recommended for those with certain health concerns (such as high blood pressure, cardiovascular or kidney disease). If you don't have a water softener...you're good to use the water inside the heater like normal!

Things You'll Need
Flashlight to find the circuit breaker, plug, and valves if it is dark
A short water hose to drain the water from the tank
A screwdriver or coin, to operate the drainage valve
A clean bucket or glass to collect the water in, or an empty gallon jug and funnel