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Are you house hunting and want to make the sure the water heater is large enough for you and your family’s needs? Maybe your current water heater will need to be replaced soon, and you’re exploring your options.

No one wants to run out of hot water, but no one likes to pay the bill for a water heater that is inefficient. If you’re wondering if a 40-gallon water heater is enough for your household, we’ll discuss how to select a water heater that will provide enough hot water without wasting money.

We will also review a few top-rated water heaters so you can have a good starting point when shopping around for a new water heater.

Is Your Water Heater Big Enough For Your Household?

If your question is, “Is a 40-gallon water heater big enough?” the answer is not a simple yes or no, as there are a few factors to consider first. If you take a quick look at these recommendations, you can see what the average household requires, but it’s important to read more to make sure you get the right size water heater for your home.

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  • A family size of one to two may benefit from a 30-gallon electric or gas water heater
  • A family size of two to three may benefit from a 40-gallon electric or gas water heater
  • A family size of three to four may benefit from a 50-gallon electric or 40-gallon gas heater
  • A household of five or more may benefit from an 80-gallon electric or 50-gallon gas water heater

Figuring Out The FHR

The quickest and easiest way to see what size water heater you need for your household is to determine the first hour rating or FHR; this measures how much water is used during the busiest time of day (which is usually right away).

The FHR should be on the Energy Guide label of your water heater, but if you need to re-evaluate your FHR or want to double-check that you’re selecting the right size, such as a 40-gallon water heater, you can use this formula (using a four-bedroom home as an example).

  • First, assign 12 gallons of hot water to each person in the house
  • Secondly, figure out maximum capacity: number of bedrooms +1
  • Your FHR number is the max. capacity number times the 12 gallons
  • In our example, the FHR is 60, which means the household needs a minimum FHR of 60

If your family FHR is smaller than 60, a 40-gallon heater may be large enough, but it depends on the type of water heater you buy. Keep in mind that the FHR refers to a storage tank water heater; as you shop around you will notice that there are a variety of water heaters.

Different Types Of Water Heaters

Storage tank water heaters continue to be the most popular type of water heater for households where there is more than one person or for people who like to shower and run the dishwasher at the same time.

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Many people replace their old storage tank heater with a newer one of the same style. Why? People are familiar with how their water heater works, and they are less likely to have to make any other upgrades. Other than storage tank heaters, the following water heaters are other options to consider:

  • Tank less or “On Demand”: We love them but there are things to consider before you buy. When you see 5.7 GPM that isn’t alway true. Check your incoming water temperature. If you live in the midwest your incoming water temp is much lower which means the heater has to work a lot harder to heat the water reducing your GPM. You must de-scale the heater at least once per year. Because the incoming water is flash heated dissolved solids or scale is released from the water and it sticks to the heat exchanger. As the scale builds the efficiency drops so you have to schedule periodic maintenance or learn to do it yourself.
  • Heat Pump or “Hybrid”: Only ideal for mild climates
  • Solar: Best for warm climates, takes awhile to recoup costs
  • Condensing: Ideal for households that need more than 55 gallons

For this article, we will continue to focus on storage tank water heaters as they continue to be the most popular type of water heater and it’s easy to find a lot of 40-gallon options.

Can You Make A 40-Gallon Water Heater Work For Your Home?

What if you’re FHR suggests that you’d benefit from a water heater that holds more than 40 gallons or what about if you’re on the cusp of a 40-gallon or 50-gallon storage tank heater? You might run into this problem if you don’t have the budget for a new water heater or the one you have is in excellent condition (and you’re not ready to replace it).

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Having a water heater that’s too small for your household is not the end of the world. At most, it can be inconveniencing, and someone might end up taking a cold shower. You may have to make a few changes to your routine to better disperse your hot water, such as not running the washing machine while taking a shower in the morning.

Ideally, you want a water heater that fits your household perfectly, but sometimes it’s not always possible. Make the adjustments you need to until you can purchase a new water heater that is sized perfectly for your household.

Do You Have A 40-Gallon Water Heater Household? Here Are Some Best-Sellers To Consider

Whether you’re upgrading (or even downgrading) the size of your water heater or you need to replace your heater, there’s a good chance that today’s 40-gallon heaters are a bit different than the one that’s in your home.

While the design and function of water heaters haven’t changed much, they have become more energy efficient overall (regardless of the type), which means that the size of some have changed. Since April of 2015, water heaters are typically two inches wider and two inches taller.

Depending on where your water heater is, this may not affect anything, but it’s important to keep in mind while shopping for a new heater. If you haven’t purchased a water heater in a while (or are buying your first one) you may have some features to consider depending on whether you choose an electric or gas water heater.

Features and Accessories To Consider

Many of today’s water heaters have features like dry-fire protection, are high efficiency, intuitive technology, and even Wi-Fi capabilities. If you select a water heater with any of these features, it may affect the cost of the water heater a bit, but the features can also lengthen the lifespan of your new water heater.

As you shop around you may also notice that water heaters come with accessories. You may or may not need them for your water heater, but it’s best to talk with a store associate to see if it’s a good choice for you.

Some accessories you may see are expansion tanks (which prevent thermal expansion of the water inside your heater. These were not required 20 years ago but its very commonly a code requirement), timers to help save money and energy, water alarms to detect leaks, water heater blankets or pans, and water heater stands. Again, these may not be important or necessary for you, but it’s good to know what’s available.

Ready to for some 40-gallon heater recommendations? Check out some of the top-selling brands.

A.O. Smith

AO Smith 40 GAL 36,000 BTU Water Heater
  • 40 gallon tank
  • 36,000 BTU gas burner
  • GCR-40 standard vent

A.O. Smith is a popular manufacturer of residential and commercial water heaters. Not only do they make standard storage tank water heaters, but they also manufacture other types like tankless, hybrid, and others that we mentioned earlier.

You can buy A.O. Smith online or at big box home improvement stores like Lowe’s.

General Electric

GE WR51X10109 Water Tank Heater
  • This is an O.E.M. Authorized part
  • Fits with various GE brand models
  • Oem part # WR51X10109

GE is a top-selling manufacturer of home appliances and water heaters are just one of the many that the company manufactures. GE manufactures both gas and electric water heaters, and they specialize in energy-efficient water heaters. You can find GE water tanks online and in home improvement stores like Home Depot or specialized or independent stores.


Kenmore 9003540 Water Heater Pilot Assembly Genuine Original Equipment...
  • This part is compatible with models including;...
  • This is a manufacturer substitution. Part may differ in appearance but is a functional equivalent to prior parts...
  • Genuine Original Equipment Manufacturer (OEM) part. Compatible Brands: Kenmore

Like General Electric, Kenmore has a long history of selling a variety of household appliances. They specialize in gas and electric water heaters that are available in a variety of styles and sizes. While Kenmore is a brand that is exclusive to Sears, you can also find Kenmore water heaters for sale online.


Rheem RTEX-18 18kW 240V Electric Tankless Water Heater, small, Gray
  • External digital thermostatic control with LED display (+/1 degree accuracy)
  • Most advanced self-modulation, adjust power to meet hot water demand
  • Durable Copper immersion two heating elements, field Serviceable. Flow Rate- up to 4.4 GPM

Rheem is a leading manufacturer of water heaters, and they specialize in a variety of types and sizes. Depending on the style of water heater you need, you can find a 40-gallon heater online, at a big box home improvement store, or at through your local plumbing or heating company.


Like GE and Kenmore, Whirlpool is a popular brand that many households recognize due to their extensive collection of household appliances. Similar to other top-selling brands, Whirlpool manufactures and distributes a variety of water heaters that can be purchased online or in stores.

Other Brands

If you find a water heater that is not one of the brands we recommend above, it doesn’t mean that it’s not a high-quality water heater. Make sure to read customer reviews to get a better idea of the company and their product.

While it’s tempting to do all of your shopping online these days, it’s may be best to visit a brick and mortar store and talk to a sales associate who specializes in water heaters. If you have questions about certain brands or what type of water heater to buy, it’s best to talk to someone in person.

There may also be rebates, warranties, and other information available in-store that’s not available when you purchase a water heater online.

Should You Install A 40-Gallon Water Heater Yourself or Hire A Pro?

Once you’ve selected a water heater for your home, you might be debating whether or not you should install it yourself or hire a pro. According to Home Advisor, the average cost for a 40 to 50-gallon water tank, with installation, is about $890.

Keep in mind that this is an average and the price may vary depending on the brand of water heater you choose and other factors.

You may be tempted to replace and install a water heater yourself. While this is a DIY project that many people do successfully, it can also be very dangerous (particularly if you have little experience with water heaters).

Depending on where you live, it may be unlawful to install your own water heater without having it inspected to ensure it’s up to code. Before you attempt to replace and install a water heater in your home, check what the rules are in your city. Even if homeowners are allowed to install a water heater themselves, you might want to invest in having a professional install the heater.

If you hire a professional to install your water heater, not only do you not have to worry about hauling the water heater from the store, but you don’t have to second guess if you’ve installed it correctly. When you hire to have the installation done, they will also take the old water heater away and dispose of it, so that’s one less thing to think about doing.

Another plus to hiring someone to install the water heater is that if it malfunctions shortly after installation, it is most likely covered by a warranty. If you install your own water heater and something goes wrong, you might have to hire someone to come and fix the problem. In many cases, it’s best to skip the risks and pay a little more for someone else to install it properly.

Last update on 2021-09-18 at 01:41 / Affiliate links / Images from Amazon Product Advertising API

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