What Size Water Heater Do I Need for My House?

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Every new homeowner looks forward to their new house. They can decorate how they want, stock their kitchen with the foods they enjoy, and make changes to the home as they see fit. One thing many homeowners might not think about is the size of the water heater they need. You want to ensure that your water heater can handle the expectations of hot water usage. Too small of a water heater will result in someone ending up with a cold shower.

A Rough Estimate of Water Usage Needs

To truly know what size water heater tank you need, find out exactly how much water you are using during the busiest “hot water use hour” in your household. This might be in the morning when everyone in your household is taking showers or at night when both the dishwasher and the washing machine are running. However, most families can get by knowing the rough calculation of how much water they will potentially use. Here are our plumbing experts’ rough estimates:

Household Size

Size of Water Heater

1-2 people

30-40 gallons

2-3 people

40-50 gallons

3-4 people

50-60 gallons

5+ people

60-80 gallons

These are just loose estimates based on average water usage of families around the same size. Every household, however, is different so your water needs may vary. For example, a very conservative water usage family of five may be able to get away with a 30-gallon tank, while a couple who likes long hot showers may find they need a 50-gallon tank. It all depends on your family’s personal needs.

Knowing Your Hot Water Usage Needs

The first step into finding out your exact water usage needs is to determine your peak hot water hour. For example, this is often in the mornings when everyone is taking a shower, but if your family showers at different times throughout the day, it is when you are using the most water-based appliances, such as a dishwasher and washing machine.

Calculating How Much Water Is Being Used During Your Peak Hour

Once you have pinpointed which hour of the day you use the most water, it is time to calculate how much water is being used. We have made a small chart of how much water is being used during everyday activities.

Water Usage

Average Gallons of Hot Water Used


10 Gallons


0.5 Gallons per Minute

Hand washing or dishwashing by hand

2 gallons per minute

Automatic Dishwasher

6 Gallons

Clothes Washer

7 Gallons

Calculate how much of these activities you do in an hour and then add up the gallon amount. Once you know how much water your household is using you can begin to look for a water heater.

When Looking for a Hot Water Heater

When you are searching for your water heater, pay close attention to the FHR (first-hour rating). This number will tell you how many gallons of hot water the water heater can provide in an hour, starting with a full tank. Invest in a water heater that will match your family’s demand at your peak hour.

Need Help Finding or Installing Your New Water Heater?

Your expert team at Roto-Rooter Plumbing & Drain can help you install the perfect water heater for your family! Our experts are available to help your family 24/7 and can handle any plumbing challenge you throw our way. With a reputation like ours, why would you turn to anyone else? Contact your trusted plumbing team at Roto-Rooter Plumbing & Drain today!