Choosing a New Water Heater: A Guide

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Determining the Size of a Storage Tank Water Heater

WARNING! Luxurious soaker tubs like the one pictured can consume more than 120 gallons of hot water.
© Salmon

After selecting your preferred fuel type, the next step is to figure out the appropriate size of water heater that can meet your needs. If you are replacing an old unit, consider if it provided sufficient heat consistently. If not, you may need to upgrade to a larger size. Additionally, think about your future plans, such as starting a family or accommodating guests, to determine if a larger heater is necessary. Once you have taken these factors into account, you can determine the appropriate size for your new water heater.

For storage tank heaters, the amount of water it holds and the recovery rate – the amount of water it can heat in an hour – are two crucial factors in determining the size. The Energy Guide sticker displays the First Hour Rating (FHR), which shows the recovery rate. A 30 to 40 gallon heater would be sufficient for a two-person household, while a 40 to 50 gallon tank is ideal for three to four people. For households with five or more people, a 50 to 80 gallon model is recommended. Gas heaters have a higher FHR than electric models, which allows for a smaller tank with the same EF rating.

To determine your specific needs, estimate your peak hour demand and look for a heater within a few gallons of that amount. The following are estimated gallon usage for various household tasks:

  • Shower – 12
  • Bath – 9
  • Shaving – 2
  • Shampoo – 4
  • Hand and face wash – 4
  • Dishwashing by hand – 4
  • Dishwasher – 14
  • Food preparation – 5
  • Washing machine – 32

[source: U.S. Department of Energy]

Multiply the gallon usage by the number of times each task occurs during peak hour to determine the total gallon usage. For example, if three people in your household take morning showers, multiply 20 gallons by three to get 60 total gallons used. If you run the dishwasher during that same hour, add another 14 gallons for a total of 74 gallons. This is your peak hour need, which should be indicated on the Energy Guide sticker. If space is an issue, consider a “lowboy” model which is shorter and wider but can hold the same capacity as taller models.

For more information on appliances, home renovation, and energy savings, please refer to the links below.

You Can Be an Energy Star

The yellow Energy Star sticker shows the efficiency of any appliance. For water heaters, the energy factor (EF) is listed. This is the ratio of hot water produced to energy used over a 24-hour period. For optimal efficiency, choose a high EF rating.

To save time in your research, you can refer to the Consumer’s Directory of Certified Efficiency Ratings for Residential Heating and Water Heating Equipment, which is a comprehensive list of EF ratings. This directory is published twice a year and can be accessed online or at your local public library.

For more information on related topics, check out the following articles: How Hot Water Heaters Work, How House Construction Works, How Home Thermostats Work, How Selling a House Works, How Green Building Works, How LEED Certification Works, What’s the one thing you can do to increase the value of your home the most?, How to Fix a Shower Head, How Air Conditioners Work, How Power Grids Work, How Carbon Footprints Work, How House Flipping Works, and How Buying a House Works.

You can also find additional resources by visiting the Department of Energy, This Old House, the U.S. Green Building Council, the Consumer’s Guide to Energy Efficiency, and the National Ground Water Association.

Sources for this information include the U.S. Department of Energy,,, the American Council for an Energy Efficient Economy, This Old House,, and Home Energy Magazine.


1. What are the different types of water heaters available?

There are several types of water heaters available, including traditional tank water heaters, tankless water heaters, heat pump water heaters, solar water heaters, and condensing water heaters. Each type has its own advantages and disadvantages, so it’s important to consider your specific needs and budget before making a decision.

2. What size water heater should I choose?

The size of water heater you need depends on several factors, including the size of your household, the number of bathrooms and appliances that use hot water, and your daily hot water usage. A general rule of thumb is to choose a water heater with a capacity of 10-15 gallons per person in your household.

3. How can I improve the energy efficiency of my water heater?

You can improve the energy efficiency of your water heater by insulating the hot water pipes, lowering the temperature setting on the thermostat, and installing a timer or demand control system. Additionally, upgrading to a more energy-efficient model, such as a tankless or heat pump water heater, can significantly reduce your energy costs over time.

4. What is the average lifespan of a water heater?

The average lifespan of a water heater depends on several factors, including the type of water heater, the quality of the installation and maintenance, and the level of usage. On average, traditional tank water heaters last between 8-12 years, while tankless and heat pump water heaters can last up to 20 years with proper maintenance.

5. How much does a new water heater cost?

The cost of a new water heater varies depending on the type and size of the unit, as well as the cost of installation. Traditional tank water heaters typically cost between $300-$1,500, while tankless and heat pump water heaters can cost between $1,000-$4,000. Solar water heaters can cost upwards of $5,000, but may be eligible for federal tax credits and other incentives.

6. What is the best brand of water heater to buy?

There are several reputable brands of water heaters available, including Rheem, Bradford White, AO Smith, and Navien. However, the best brand for you depends on your specific needs and budget. It’s important to research the features and reviews of each brand before making a decision.

7. What is the warranty on a new water heater?

The warranty on a new water heater varies depending on the manufacturer and model. Traditional tank water heaters typically come with a 6-10 year warranty, while tankless and heat pump water heaters may have a warranty of up to 20 years. It’s important to read the warranty information carefully and understand what is covered and for how long.

8. What are the installation requirements for a new water heater?

The installation requirements for a new water heater depend on the type of unit and the local building codes. Generally, water heaters must be installed in a safe and accessible location, with proper ventilation and gas or electrical connections. It’s recommended to hire a licensed professional plumber or HVAC technician to install your new water heater.

9. Can I install a water heater myself?

Installing a water heater yourself is possible, but it’s not recommended unless you have experience and knowledge of plumbing and electrical work. Improper installation can result in serious safety hazards and damage to your home. It’s recommended to hire a licensed professional plumber or HVAC technician to ensure proper installation.

10. How often should I flush my water heater?

Flushing your water heater is important to remove sediment and prevent buildup that can decrease the efficiency and lifespan of your unit. It’s recommended to flush your water heater at least once a year, or more frequently if you have hard water or notice a decrease in performance.

11. How can I tell if my water heater needs to be replaced?

There are several signs that your water heater may need to be replaced, including leaks, rust or corrosion, strange noises, and a decrease in hot water supply. If your water heater is over 10 years old and showing signs of wear and tear, it’s likely time to consider replacing it.

12. What should I do if my water heater stops working?

If your water heater stops working, the first step is to check the pilot light (if you have a gas unit) and the circuit breaker (if you have an electric unit). If these are functioning properly, it’s recommended to call a licensed professional plumber or HVAC technician to diagnose and repair the issue.

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