​​​​​​​​​​​​​​​​​Residential Water Heater Sizing Guide

Get all the answers to your water heating questions before you buy.

When something as important as your water heater needs to be replaced, you want to be certain of all the facts before you buy. That's why we've tried to answer all your questions here, so when it's time to buy, you feel confident you've made the right choice. 

What size water heater do I need? 

We sell 30-, 40-, 50- and 75-gallon natural gas water heaters. The experts at Home Service Plus can help you determine the best size for your needs. 
Simply call 612-342-4610 in the Minneapolis/St. Paul, MN metro area or 1-877-HSP-1664 for a price quote, to place an order, or to answer any other questions you may have. 

Is fast hot water recovery important to you? 

In addition to size, HSP features water heater models with high BTU capacity for faster recovery of hot water to best fit the needs of your family and lifestyle. For a general idea, the following two methods will help you determine the ideal size water heater for your home. Keep in mind, these are general guidelines, since no two family's hot water needs are exactly alike. 

Family needs 

The first method depends on the number and ages of family members, how you wash dishes and clothes, and the number of bathrooms in your home. For example, the needs of a family of two with one bathroom and a clothes washer should be adequately met with a 30-gallon water heater. For every additional bathroom in your home, add another 3-1/2 gallons to the tank capacity. If you use an automatic dishwasher, add another five gallons to this total. 

Residential Water Heater Sizing Guide 

Family Size Demand Gallon Capacity
1-2 peopleHigh
40 to 50 gallons
2-3 peopleHigh
40 to 50 gallons
3-4 peopleHigh
50 to 75 gallons
5+ peopleHigh
75 gallons
50 gallons

First-Hour Rating 

The second method to consider is the first hour rating; it tells you the amount of hot water the water heater can deliver in one hour. Follow this procedure to use the first-hour rating: 
  • Determine the hour of the day when you use the most water. 
  • Use the Activity Chart table to find the quantity of hot water you use for each activity during that hour.
  • Add all the quantities for that hour. The total is your first-hour rating. 
  • Choose a water heater with a first-hour rating close to the total amount of hot water you use during the hour you selected. The first-hour rating also includes the recovery rate. This is a combination of how much water is stored in the water heater and how quickly the water heater can heat cold water to the desired temperature. 
Activity Hot Water Used
Clothes washer       25 to 40 gallons per load 
Dishwasher  ​5 to 10 gallons per load
Hand dishwashing 3 to 4 gallons
Tub bath  15 to 25 gallons
Shower 3 gallons per minute
Bathing an infant  2 gallons
Shaving  2 to 3-1/2 gallons
Shampooing  5 gallons
Hand washing  1 to 2 gallons
House cleaning  5 to 12 gallons
Food preparation  3 to 6 gallons
*BlueFlame.org, Minnesota Blue Flame Gas Association

The Home Service Plus experts can help you choose the ideal water heater to meet your household needs. For complete information on natural gas water heaters and other things to consider when buying, review the facts on natural gas water heaters​