Your Water Heater Is an Emergency Water Tank

If the water stops or your town issues a do-not-drink order, you might already have one of the biggest emergency water supplies in the neighborhood without knowing it. A typical tank water heater holds roughly 30 to 80 gallons. That's days or weeks of drinking water for a family.

01When to use it

• The water is shut off after a main break, a freeze, or an outage that knocked out the water system.
• A boil or do-not-drink order is issued.
• You need water and your stored supply is running low.

If the town's water may be contaminated, close the water heater's cold-water inlet valve right away (or shut off your main) so contaminated water doesn't flow into the tank and mix with the clean water.

02How to get the water out

1. Turn off the power or gas. For an electric heater, turn it off at the breaker; running it empty can burn out the elements. For a gas heater, turn the gas valve to "pilot" or "off" as the manufacturer directs.
2. Let it cool. The water is hot enough to burn you. Wait a few hours if you can.
3. Close the cold-water inlet valve at the top of the tank.
4. Open a hot-water faucet somewhere in the house. That lets air into the tank so the water flows out.
5. Attach a short hose to the drain valve at the bottom, or put a clean container under it.
6. Open the drain valve slowly.

03The sediment

The first water out may be cloudy or full of rust and sediment. That's normal; tank water heaters collect sediment at the bottom. Let it settle or filter it through a clean cloth or coffee filter. If you're unsure about the water, treat it. See water purification.

If your water heater hasn't been flushed in years, the drain valve might be clogged. Flushing the tank once a year is good maintenance anyway, and you'll know the valve works.

04Refilling it

When the water comes back on and is safe:

1. Close the drain valve.
2. Open the cold-water inlet.
3. Leave a hot-water faucet open until water flows steadily, with no sputtering air.
4. Only then turn the power or gas back on. Turning on an electric water heater with an empty tank can burn out the elements right away.

05Tankless water heaters

Tankless heaters don't store water, so this doesn't apply. If you have one, store more water.

06Other water in your house

• Pipes: shut off the main, open a faucet at the top of the house, then drain from the lowest faucet. You'll get a few gallons.
• Ice cubes in the freezer.
• Toilet tanks (not bowls), if no cleaning tablets are used, can be treated for drinking.

07Store water too

The water heater is a backup. A household should still store water: the usual guidance is at least one gallon per person per day for several days. See water storage: how much and how to rotate.

Knowing where your water heater's valves are takes five minutes. Go look today.

Photo: NZERTF Basement by National Institute of Standards and Technology, Public domain.

Related: Sanitation and Hygiene When the Water Is Off · When the Toilet Won't Flush: Sanitation in an Outage