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What Size Water Heater Do I Need?

Whether it has been over 10 years since you installed your water heater or you are just ready to upgrade to a more efficient or…

May 05, 2026
What Size Water Heater Do I Need?

Whether it has been over 10 years since you installed your water heater or you are just ready to upgrade to a more efficient or bigger water heater, you are going to want to know what size water heater to get. If a new water heater is in your near future, then take some time to read through this article and consider the factors. Your friends at Mr. Rooter Plumbing of New Jersey are always happy to help you by answering questions or conces and scheduling a flexible appointment. Our qualified plumbers are regularly trained and equipped with the latest tools and technology so that your water heater replacement goes as smoothly as possible.

Our Customers Reviews

Larry R.

Howell Township, NJ

It was a late Saturday night. We had a super stubborn clog in some old galvanized pipes. Mr. Rooter send out Phil. Phil was great! He found the problem pretty quick. With determination and professionalism he final got it cleared out. I would recommend Mr. Rooter and Phil to anyone! He even cleaned up. We are so happy we choose Mr. Rooter!

Rose Bernard

Red Bank, NJ

We had a plumbing emergency and found Mr. Rooter while frantically searching for a 24-hour plumber. We feel like we hit a gold mine. Not only did we get a timely response. Everyone at Mr. Rooter was friendly, professional, competent and went above and beyond. Our plumber, Phil, was extremely helpful and gave us tips we could use moving firwars. Not to mention, the cost was extremely reasonable.

Joseph Chis

Hillsborough, NJ

Had sewer water backup in toilet and tub. Received callback as promised and arrived early. The tech determined we needed the main line to be cleared. He quickly located the opening and had us cleared in minutes. Very happy with the service. I was not prepared for the fee but it was an emergency.

Christopher Cox

Little Silver Township

Plumber, Phil, came out on short notice on a Saturday night and fixed our issue quickly, professionally and courteously. I contacted a different, well known plumbing company right before Mr. Rooter. The receptionist was rude and they didn’t call me back to say they couldn’t make it until after Phil left! The Mr. Rooter receptionist was very nice and they called me back quickly. I’m glad they did.

Debbie Dimitrion

Colts Neck, NJ

I just wanted to say James did a great job at my house. Excellent service, professional and very nice. Thank you so much for helping me with my plumbing problem. Did wonderful job.

Rachel Turunen

Jackson Township

I was very happy that I went with Mr. Rooter’s. The service was very quick and up front. Jessie James was very helpful answering my questions and replacing my hot water heater. He was pleasurable to do business with. If another problem arises in my home, I will be using this company again.

William Holden

Brick Township, NJ

A thorough, professional, pleasant experience. I had a back-up in the 50 year-old pipes of my new home. I called Mr. Rooter to have them locate the blockage, snake the line, and then use their video snake to get a visual of the integrity of the pipes. I’m glad that I called and will use them again for future needs.

LarJ MarJ

Oakhurst, NJ

You get what you pay for. Edwin Robles of Central NJ educated me as a 1st time homebuyer on why and what he was repairing, prevention, PROMPT,(on a sunday at that!) clean, knowledgeable, super professional but DOWN TO EARTH and at a REASONABLE PRICE! Sewer pipes unclogged and main water line fixed. I was no longer crying once job was thoroughly executed. After all $#@* $tinks but somebody has to do it and I HIGHLY recommend him and this company for a job well done. THANK YOU VERY MUCH!!

Margie Rafferty-Criscione

Ocean Township

Absolutely lovely office staff! I always knew when the repair person was coming. Lorenzo our repair guy was awesome, I really don't think there is anything he can't do. He looks young, but don't let that fool you! So happy all the repairs are behind us. We really just did a one-stop shopping and decided to have everything we've put off fixed because it was such a tremendous experience!

What Size Water Heater Do I Need?

Types of Water Heaters

Before we dive into deciding the right size of the water heater, let’s go over the two main types of residential water heaters. Each has its own benefits as well as drawbacks, so read through each to decide which is best for your household.

  • Storage tank water heaters are the most common type of water heater. Just as the name suggests, they have an insulated tank that stores hot water. There are electric- and gas-powered models available. Storage tank water heaters have a low upfront installation cost, but they can run up your electricity or gas bills significantly compared to the other types.
  • Tankless water heaters save space in your property and are more energy-efficient in the long run, but they are generally more expensive up front. Tankless water heaters produce hot water on demand.

Rather than a capacity restriction, they have a flow-rate restriction.

Fortunately for homeowners in New Jersey, Mr. Rooter Plumbing of New Jersey has certified plumbers who specialize in repairs, replacements, and installations of both types of water heaters, so do not hesitate to call for assistance.

Choosing A Storage Tank Water Heater

The output for a storage tank water heater is more or less fixed. Water inside the tank is heated and available until used. Therefore, the tank capacity (measured in gallons) is the figure to pay attention to when choosing your storage tank water heater. The general rule of thumb is to have about 10 to 15 gallons per person in the household. A two-person household can make do with a 24- to 30-gallon tank while a 40- to 50-gallon tank is good for a 4-person household.

Selecting A Tankless Water Heater

Tankless water heaters, also called on-demand water heaters, will heat water as needed. So, flow rate is the specification to pay attention to when selecting a tankless water heater. The metric used is “gallons-per-minute” (gpm). Here is a list of typical flow rates that common fixtures use:

  • Faucet: 1 gpm
  • Shower: 2.5 gpm
  • Bathtub, Dishwasher, Laundry Machine: 3 gpm

Calculate the maximum amount of hot water you would expect to use and choose your tankless water heater accordingly. For example, if you expect to use, at a maximum, one dishwasher (3 gpm), one shower (2.5 gpm), and a faucet (1 gpm) at the same time, then you will need a tankless water heater with a minimum of 6.5 gpm (3 gpm + 2.5 gpm + 1 gpm).


 

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