We preppers talk a lot about water storage. Water is critical to survival and really you can’t have too much of it stored. However, in the event of a true crisis, on top of the cases of bottled water you have squirreled away, you likely already have a fairly sizeable supply of water at your fingertips.
The average water heater contains about 30 gallons of water at any given time, except perhaps right after your teenager has taken their daily 90 minute shower. For all intents and purposes, a water heater really just amounts to a giant glass and metal thermos with an attached heating element.
Homeowners should already know where their water heater is located, often in a basement or utility closet. Those who live in apartments and condos might have to do a little hunting to find theirs. Again, though, check the building basement first. If you live in a mobile home, the water heater is sometimes found behind a false wall in a closet.
Draining the Water
Draining the water from a water heater is a fairly straightforward process. Start by turning off the water supply coming into the heater. This can be important as if the water supply becomes tainted at some point down the road, you don’t want that flowing into your water heater.
If your water heater is electric, turn off the power at the circuit breaker panel. Do this even if the power is already out in the area. The heating element inside a water heater can be come damaged if it turns on and there isn’t any water inside. If you have a gas water heater, turn the thermostat to Pilot.
Toward the bottom of the water heater, you’ll see the drain valve. It looks like a faucet. Connect a garden hose to the drain valve but do not open the valve just yet. First, open a hot water faucet in your bathtub or sink, being sure to plug the drain so as to save any water that comes out, of course.

Run the hose from the drain valve to a bucket, then open the valve. This water may still be rather hot, so be careful. It is best to have several water containers at the ready as, again, you have about 30 gallons or so of water to drain. You don’t have to drain it all at once but that might be ideal, depending on the circumstances.
As you get the last of the water out, you may notice some sediment. This stuff isn’t going to harm you, it is merely mineral deposits. Just let it settle to the bottom of your bucket.
Restarting Your Water Heater
When it comes time to put your water heater back into use, start by making sure the drain valve is closed. Turn on the water supply going into the water heater and let it fill. Turn on the power or turn the thermostat back up. Once the temperature is back to where it should be, you’ll need to test the pressure relief valve on the side of the water heater. The instructions for doing so should be printed right on the heater or on a tag attached to that valve. If it doesn’t test properly, get in touch with a licensed plumber to get it fixed ASAP.
More resources for water purification
- Big Berkey Water Filtration System — dependable brand, recommended
- Katadyn Gravity Water Filter — 1 to 6 persons
- Lifestraw Personal Water Filter — inexpensive and lightweight
- The Prepper’s Water Survival Guide by Daisy Luther
- Sawyer Mini Water Filter — a good size for emergency kits. I keep one in my suitcase for family travel.
- Survival Mom: How to Prepare Your Family for Everyday Disasters and Worst Case Scenarios by Lisa Bedford
I thought my teenager was the only one that took those crazy-long showers. Glad to hear I’m not alone! 🙂
Even after the long shower, your water heater is FULL…..when some goes out some goes in….can’t have a shower without pressure.
And one needs to open a hot water faucet to get the tank to empty.
My bad……..missed that part………
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If you seriously will rely upon your water heater for emergency water, then you should know that as it ages, it can have a build-up of calcium and aluminum sludge. This can block the drain faucet. Besides, who wants to drink jellied aluminum sludge?
So, replace the typical gate valve with a ball valve that can be reamed out if necessary. Replace the aluminum anode with one made of magnesium. Annually, flush the tank and check the condition of the anode. The anode is crucial. Tanks with a 6-year warranty have 1 anode, while those with a 12-year warranty have 2 anodes. Why doesn’t anyone teach us this stuff when we are young adults?
See this article on using the water heater for emergency water.
http://www.waterheaterrescue.com/Longevity/emergency-preparedness-and-water-heaters.html
Also, see the page on Water Heater Basics for lots of good information.