How to drain a water heater

Learn why you need to perform this essential maintenance task

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    It’s hard to imagine modern life without water heaters. Invented in 1889 by Norwegian engineer Edwin Ruud, the water heater has undergone many design improvements since it first appeared.

    Nowadays, water heaters come in two basic types: tank-style and tankless. Both types can be fueled by electricity, propane or natural gas. Regardless of the type you own, learning how to drain a water heater is vital if you want to maximize its working life.

    Key insights

    • All water heaters need to be drained at least once a year to avoid sediment buildup, and every four to six months if you have hard water.
    • Not draining your water heater will decrease its efficiency by “insulating” the outgoing water from the heat source.
    • If you avoid draining your water heater, you might notice a decrease in water pressure and chunks of sediment coming out of your taps.

    Safety precautions to consider before you drain a water heater

    Although draining a water heater isn’t complex, it’s important to follow proper safety precautions.   The first step to the safe draining of both propane and natural gas-fueled heaters is ensuring gas can’t flow into your heater during draining. “Extinguish the pilot light and shut off the gas valve first,” said Matt Little, a veteran plumber and co-owner of Damien McEvoy Plumbing.

    Another safety issue stems from the fact that the water in a tank-style unit will still be hot even after you’ve disconnected the power or shut off the gas supply. “Be cautious, since the water can scald you,” said Little. If you’d rather eliminate burn risk entirely, wait an hour or two to give the water in your tank-style heater time to cool.

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    What kind of water heater do I have?

    Before draining your water heater, you need to know what type it is. Chances are you know this already, but if not, here’s how to identify whether your heater is tank-style or tankless, and how it’s fueled.

    Tank-style heaters are large and cylindrical in shape. Electric tank-style heaters will be hardwired into your home’s electrical system with a cable. Propane and natural gas-fueled models will have an incoming gas line plugging into the heater with a shut-off valve.

    Tankless water heaters are much smaller, generally rectangular and wall mounted. Like tank-style units, they’ll either have an incoming gas line or be wired into your home’s electrical system.

    How to drain a water heater

    Gather the necessary supplies and follow the steps below to drain your water heater.

    Materials needed

    You’ll need the following materials:

    • Garden hose of sufficient length to reach your floor drain or bathroom drain
    • Large oil drain pan (if floor drain or bathroom drain isn’t available)
    • Adjustable wrench or slot screwdriver (depending on the configuration of your drain valve)


    Follow these steps:

    • For propane or natural gas-burning water heaters, begin by turning off the gas valve and extinguishing the pilot light. If you have an electric heater, locate the electrical breaker it’s connected to on your service panel, and flip it to the off position.
    • Shut the cold water intake valve to prevent water from entering your heater.
    • Connect a garden hose to the drain valve near the bottom of your heater (this applies whether your unit is tank-style or tankless).
    • Route the other end of the hose to the nearest floor drain or shower stall. If you don’t have a household drain handy, you’ll need to drain your water heater into a bucket instead.
    • For tank-style heaters, you’ll probably need to skip the hose and drain directly into a large, clean oil pan since a regular bucket will likely be too tall.
    • Keep in mind that if you use a hose, its draining end needs to stay below the heater’s drain valve so gravity can take effect.
    • For tank-style heaters, wait an hour or two for the water to cool before draining. When your hose or bucket is positioned properly, use an adjustable wrench or screwdriver to open your water heater’s drain valve.
    • Allow water and sediment to drain out, keeping an eye on the flow. If you’re using a bucket you’ll need to periodically close the drain valve when the bucket is full, dump it outside or down the nearest drain in your home, then return with the empty bucket and repeat the process. Continue draining until the water is fully clear and sediment-free.
    • Disconnect the hose and close the drain valve once all the sediment has been drained from your heater. Open the cold water inlet valve to refill your heater, then switch the breaker back on, or re-ignite the pilot light and open the gas supply valve.

    Tips for maintaining your hot water heater

    Take a look at a few ways you can maintain your water heater.

    Keep your water heater working well by draining it at least once a year.
    • Consider running vinegar through your tankless water heater twice a year to dissolve mineral deposits and improve efficiency.
    • Replace the anode rod in your tank-style heater at least every five years, and maybe more often, depending on how quickly it corrodes.
    • Consider adding demineralizing equipment to your water system if you have hard water. This makes things easier on your water heater and allows draining to happen less frequently.
    • Get a more accurate perspective on the sediment in your water during draining by placing a white cloth over the top of your bucket to collect the sediment while letting the water drain through.
    • If you’ll be traveling and have a tank-style heater, shut it off if it’s electric to save energy and wear and tear. If your heater is gas-powered, switch it to away mode to keep the pilot light burning, but avoid heating water.

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      Bottom line

      Every water heater needs regular draining, whether it’s a tank or tankless model. If you don’t feel comfortable draining your heater yourself, hire a professional to service it at least once a year.

      “Draining different types of water heaters, including propane water heaters, tank-style water heaters, and natural gas water heaters is an important maintenance job that should be done regularly to avoid sediment build-up and to extend the life of your water heater system,” Little said. “If you’re ever unsure or uncomfortable with any of these tasks, it’s always a good idea to call on the expertise of a professional plumber.”

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