How Often Should You Drain Your Water Heater?

Your water heater works quietly in the background every day, heating water for showers, dishes, and laundry. But over time, minerals from your water supply settle at the bottom of the tank. That sediment buildup is one of the most common reasons water heaters lose efficiency, make strange noises, or fail earlier than they should.

Draining (also called flushing) your water heater removes that sediment and helps the unit run the way it’s supposed to. Here’s how often to do it, what to watch for, and when it makes sense to call a professional.

Why Draining Your Water Heater Matters

Every time your water heater fills up, dissolved minerals — mainly calcium and magnesium — come along for the ride. As the water heats, those minerals separate and sink to the bottom of the tank. Over months and years, that layer of sediment grows.

This is especially common in areas with hard water, like much of the San Gabriel Valley and greater Los Angeles area. The harder your water, the faster sediment accumulates.

Here’s what that buildup does:

• Reduces heating efficiency. Sediment acts as insulation between the burner and the water, forcing the heater to work harder and use more energy.
• Causes strange noises. Rumbling, popping, or crackling sounds during heating cycles usually mean sediment is being disturbed at the bottom of the tank.
• Shortens the tank’s lifespan. Excess heat trapped under the sediment layer can weaken the tank lining over time.
• Increases the risk of leaks. Prolonged overheating at the bottom of the tank can eventually cause cracks or corrosion.

While you’re draining the tank, it’s also a good opportunity to check your anode rod — the sacrificial metal rod inside the tank that protects against rust. If the rod is heavily corroded, replacing it during a flush can add years to your water heater’s life.

Draining your water heater is one of the simplest parts of regular water heater maintenance, and it makes a real difference in how long your unit lasts.

How Often to Drain Your Water Heater

For most homes, draining once a year is enough to keep sediment under control.

If you live in an area with hard water — and most of Southern California qualifies — every six months is a better target. The mineral content in local water supplies means sediment builds up faster than in areas with softer water.

What if you haven’t flushed in five years or more? It’s still worth doing, but go slowly. A tank that hasn’t been drained in a long time may have a thick layer of sediment that partially blocks the drain valve. If the water coming out looks very cloudy or the flow is weak, stop and call a plumber rather than forcing it. Old sediment can also hide corrosion you’d want a professional to evaluate.

The same applies if your water heater is ten or more years old and has never been flushed. The benefit of draining is still there, but the risk of disturbing a corroded drain valve or revealing a weakened tank lining goes up. A plumber can assess the situation and flush it safely.

Tankless water heaters have a different maintenance routine. They don’t store water, so sediment doesn’t settle the same way. But mineral scale still builds up on the heat exchanger. Most manufacturers recommend a vinegar flush once a year to keep performance consistent.

If the water heater isn’t in use — say, in a vacation home or rental that sits empty for months — draining the tank before a long vacancy prevents stagnant water from accelerating corrosion. Just remember to refill the tank completely before turning the heater back on to avoid damaging the heating element.

Signs Your Water Heater Needs Draining Now

You don’t have to wait for the calendar to tell you it’s time. These are common signs that sediment has already built up enough to cause problems:

• Rumbling or popping sounds when the burner kicks on. This is steam bubbles escaping through the sediment layer — the most telltale sign.
• Rusty or discolored hot water. If only the hot side is affected, the issue is likely inside the tank, not your pipes.
• Hot water runs out faster than it used to. Sediment takes up space in the tank, reducing the volume of usable hot water.
• Higher energy bills without another obvious explanation. The heater is working overtime to push heat through the sediment.

If you’re noticing any of these along with other warning signs, it may be worth checking for broader issues. Here’s a guide to early signs of a failing water heater that covers what else to look for.

How to Drain a Water Heater Yourself

If your water heater is in reasonable condition and you’re comfortable with basic home maintenance, flushing it yourself is straightforward.

What you’ll need: a garden hose, a flat-head screwdriver (some drain valves require one), and a place to run the hose where hot, sediment-filled water won’t cause damage (a floor drain, driveway, or large bucket).

Steps:

1. Turn off the heat source. For gas heaters, set the thermostat to “pilot” or turn off the gas valve. For electric heaters, flip the breaker.
2. Let the water cool down. Wait at least an hour, or run hot water from a nearby faucet for a few minutes to bring the temperature down. The water inside the tank can scald.
3. Connect a garden hose to the drain valve at the bottom of the tank. Run the other end to your drain location.
4. Turn off the cold water supply to the heater.
5. Open a hot water faucet somewhere in the house (this prevents a vacuum from forming in the tank).
6. Open the drain valve. Let the water flow until it runs mostly clear. This can take 10 to 20 minutes depending on how much sediment is present.
7. Briefly turn the cold water supply back on with the drain valve still open — this stirs up remaining sediment and flushes it out.
8. Close the drain valve, turn the cold water supply back on, and let the tank fill completely.
9. Turn the heater back on once the tank is full and water flows normally from the open hot faucet.

Important: Never turn a gas or electric water heater on with an empty or partially filled tank. This can burn out the heating element or damage the tank.

When to Call a Plumber Instead

Draining a water heater is a manageable DIY task for many homeowners. But there are situations where calling a professional is the smarter move:

• The drain valve is corroded, stuck, or leaking. Forcing a stuck valve can break it, and then you have a bigger problem.
• The tank is over 10 years old and has never been flushed. The risk of revealing hidden damage is higher, and a plumber can evaluate the overall condition while draining it.
• You notice water leaking from the bottom of the tank during the process. That’s a sign of internal corrosion and may mean the tank needs replacing.
• You’re not comfortable working around gas or electrical connections. There’s no shame in that — safety comes first.
• Sediment is so thick the drain valve clogs. A plumber has tools to clear the blockage or can recommend whether the tank is worth saving.

If your water heater is nearing the end of its life, a plumber can also help you weigh your options for water heater installation — whether that’s a new tank unit or upgrading to tankless.

If your water heater needs draining, maintenance, or replacement, call Western Rooter & Plumbing at (626) 448-6455 or schedule service online through our website.