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How Long Should a 40-Gallon Water Heater Stay Hot?

Imagine running out of hot water in the middle of your shower, and immediately feeling the rush of cold water stinging your skin. Now, that is a chilly inconvenience no one wants to have.

A 40-gallon water heater is common for households with two to four people. You can often find these tanks in homes with 1.5 bathrooms. If you have a 40-gallon water heater at home that quickly runs out of hot water, you might have a problem.

Find out how long your 40-gallon water heater should stay hot, and why it could be running out of hot water faster than it should.

wall hung water heater

How Long Should a 40-Gallon Water Heater Stay Hot

As an estimate, the hot water inside a well-insulated tank should stay hot for a day or two when unused. Ideally, a 40-gallon water heater can provide hot water continuously for 45 minutes and up to an hour. In reality, this amount of time depends on several factors, including:

  • How hot do you prefer your shower water to be
  • The flow rate of the showerhead
  • How long do you typically take your showers
  • How well your tank insulated
  • The recovery rate of the water tank

How Many Hot Showers Can You Get from a 40-Gallon Water Heater

In general, a typical shower uses 10 gallons of water for each use. That means, on average, you can get up to four showers from a 40-gallon water heater within the same hour. That is provided you limit your hot water use to only the showers and no other appliances.

Typically, however, you use your hot water in the dishwasher, the laundry, or even the bathroom taps for washing your hands. All these activities and appliances can significantly deplete your hot water supply.

Sometimes, you can only get two showers if you like to stay in the shower for longer or when several people are taking a hot shower at the same house. Ultimately, how many hot showers you can get from a 40-gallon water heater depends on how much water you use in the shower and elsewhere in your house.

What Is Water Heater Recovery Time?

Your water heater’s recovery rate is the time it takes to heat the water inside the tank after all the hot water has been used. Water heater recovery time depends on the size of the water heater as well as the type of water heater you have.

Gas water heaters typically work faster compared to electric water heaters. For instance, a 40-gallon gas water heater can recover in about an hour, but a 40-gallon electric water heater takes twice as long.

Why Your 40-Gallon Water Heater is Running Out of Hot Water Too Fast

If your 40-gallon water heater seems to be running out of hot water too fast, ask yourself whether it has always been a problem or is it a recent issue.

In the first scenario, you may have always run out of hot water even after trying to limit how much hot water you use. Your 40-gallon water heater is simply not enough. It’s too small for your needs, and it’s best to upgrade to a bigger tank.

But if you experienced a lack of hot water only recently, you can have one of these problems.

  • Your Water Heater is Too Old. Water heaters lose their efficiency over time, so it stands to reason that your old water heater can’t properly or thoroughly heat the water anymore.

  • Thermostat Problems. Water heaters have a thermostat used to control the temperature of the heated water. You can set the thermostat to the ideal hot water temperature that you want, but sometimes, the thermostat can malfunction or break down. When that happens, it limits your water heater’s efficiency in heating the water to your preferred temperature.

  • Sediment Buildup. Unless you’re using filtered tap water, the water source that enters your home could carry sediment. These tiny mineral particles can build up at the bottom of the tank, and over time, the sediment buildup can reduce the amount of hot water your water heater can store.

When to Replace Your Water Heater Tank

It’s easy to forget to upgrade household appliances, such as a water heater, as the family grows. But suppose the number of people in your household increases. In that case, consider replacing your existing water heater with a bigger one to accommodate the growing needs of your family and keep everyone happy and comfortable.

Here are some figures to help you select an appropriate water heater tank for your home.

  • Two people or less: 30-40 gallons
  • 2-4 people: 40-50 gallons
  • 4-5 people: 50 to 60 gallons
  • Five or more people: 60 gallons or more

Also, consider adding an extra 10 gallons per additional person.

When to Replace the Entire Water Heater System

If you recently noticed that your 40-gallon water heater always runs out of hot water, it could be that the system is already too old to function efficiently. In this case, replacing the entire water heater system is your best option.

If your water heating system at home is ten years old or older and can no longer heat water as well as it once did, it’s time to replace it.

But if you do replace the entire unit, consider getting an upgrade to a bigger tank to accommodate everyone’s needs in your house. A tankless water heater is another option for larger households as it heats water as needed.

Adam McCoy

Adam is an HVAC expert and the owner of Mackydo's HVAC Services with decades of experience in fixing and installing air conditioning units, furnaces, and every type of cooling and heating equipment you can think of.

Adam believes that your home is your sanctuary. He loves sharing advice based on his lifelong experience and treats every HVAC problem as if it was his own.

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