How to Get Drinking Water from Your Water Heater

How to Get Drinking Water from Your Water Heater

When the water stops flowing from your faucet, it’s easy to assume you’re completely out of options. But in many homes, there’s still a large amount of usable water sitting quietly in one place — your water heater.

During a water shutoff, pressure loss, or contamination event, a traditional tank-style water heater can serve as a reliable backup water source. Knowing how to access it — and when it’s safe to use — can buy you valuable time.

Why Your Water Heater Can Be a Reliable Emergency Water Source

Unlike water sitting in your plumbing lines, the water inside a water heater is stored in a sealed tank. When utilities fail or pressure drops, that water often remains accessible.

Because it’s enclosed, it’s also better protected from immediate contamination than water in open containers or partially drained pipes. As long as the tank hasn’t been damaged or flooded, the water inside may still be usable even after the rest of the house goes dry.

Is The Water Safe To Drink From Your Water Heater?

In most emergency situations, yes — with some important considerations.

Your water heater is filled with the same water that comes from your tap. If your local water supply was safe prior to the outage, the water in the tank is usually safe as well. However, if your city issued a “boil water” or “do not drink” alert before service was shut off, you should assume the water in your heater is not safe to drink without treatment.

Water heaters can also contain sediment, especially in older systems or tanks that haven’t been flushed regularly. This sediment should be filtered out before consuming the water. If the water smells metallic, appears cloudy, or raises any concerns, filtering adds an extra margin of safety.

How Much Drinking Water Is in a Typical Water Heater?

Most residential water heaters hold more water than people expect.

Common tank sizes include 30, 40, 50, and even 75 gallons. A standard 50-gallon water heater can provide days or even weeks of drinking water, depending on how many people are in the household and how conservatively water is used.

At the commonly referenced guideline of one gallon per person per day, even a partially full tank can make a meaningful difference during an outage.

How to Get Drinking Water from Your Water Heater (Step by Step)

Most standard tank-style water heaters allow you to access stored water using the drain valve near the bottom of the tank. While layouts vary slightly, the process is similar in most homes.

Before you begin, make sure the water heater has not been damaged or flooded.

Step 1: Turn Off Power or Gas to the Water Heater

Shut off power at the breaker for electric units, or turn the gas control knob to “off” for gas heaters. This prevents damage and reduces burn risk.

Step 2: Shut Off the Cold-Water Supply

Locate the cold-water supply valve at the top of the tank and turn it off. This prevents new water from entering the system.

Step 3: Relieve Pressure

Open a hot-water faucet somewhere in the house. Even if no water flows, this allows air into the system so water can drain properly.

Step 4: Attach a Hose or Prepare Containers

Attach a hose to the drain valve and run it into a clean container. If no hose is available, you can carefully collect water directly, though this may be slower and messier.

Step 5: Open the Drain Valve Slowly

Open the drain valve gradually. Water may start slowly, especially if sediment is present. Let the water run until it clears, then collect what you need.

Step 6: Treat the Water if Needed

If there’s any doubt about water quality, treat it before drinking. Filtering or boiling adds an important layer of safety.

Note: This method works with traditional tank-style water heaters. Tankless systems don’t store meaningful amounts of water and generally aren’t useful as an emergency source.

Test This Process Before an Emergency

It’s a good idea to test the draining process ahead of time, so you’re not figuring it out for the first time during a crisis. Even briefly opening the drain valve helps you understand how your system works and where containers or hoses should be placed.

Important warning:
If your water heater is older, heavily scaled, or you live in an area with hard water, draining the tank can sometimes cause problems. Many older heaters are already near the end of their lifespan, and disturbing sediment or valves may trigger leaks or failures. This doesn’t happen often — but it’s something to be aware of before experimenting.

Final Thoughts

Your water heater shouldn’t be your only water plan — but it’s an excellent backup. Combined with stored water and a plan for sourcing more if needed, it adds flexibility and peace of mind when clean water becomes harder to access.