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Tankless vs Tank Type Water Heater

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That decision usually comes down to a matter of preference, although understanding the differences will help you make a better choice when you’re looking at what water heater to get.

Each type has its own advantages and disadvantages, safety factors, and applications. Here’s a quick rundown of the differences:

Tank Water Heaters

For many years, water heaters with a storage tank were the only game in town. Tank sizes typically range from 30 to 50 gallons although there are some with smaller or bigger capacities.


  • Upfront Cost – A traditional tank system is less expensive initially. Both the unit itself and the installation is typically cheaper than a tankless system for a whole house.
  • Installation – If you are replacing an existing water heater you may not have to perform any piping modifications to install the new one. Installation is simple, and there is less that can go wrong with installation of the water heater.
  • Repairs/Part Availability – Equally appealing is the fact that when repairs are necessary, most of the components can be replaced individually and with little to know prior experience, saving hundreds of dollars and expediting the repair.
  • Emergency Water Supply – With a tank system, you always have some hot water available on hand, even if there is a temporary power outage. In case of emergency where drinking water is not available, the water inside the tank can act as your emergency supply.


  • Limited Supply of Hot Water – Even with a large tank, families who bathe in succession or take long showers may discover that the last person in the shower ends up getting a cold surprise.
  • Operating Costs – This type of system is also more expensive to operate, since it has to maintain the temperature even when the water is not being used for hours at time.
  • Leaks/Water Damage – A traditional water heater has the obvious problem of having water to clean up in case of a leak or complete tank failure (unless a properly installed drain pain is in place).
  • Space Requirement – The tank is also a problem when it comes to placement as it requires a good amount of space. Most older homes have a dedicated closet just for the unit.
  • Lifespan – The components in a tank system wear out faster than a tankless unit, so the estimated life of a new unit is only 10 to 15 years.

For more information, see our Tank Water Heater Buying Guide.

Tankless Water Heaters



  • Unlimited Hot Water – There is no worry of running out of hot water in a household. Families can all shower in succession, since a tankless system can provide as much as 10 gallons of hot water a minute. Have a large soaking tub? With a tankless model you're not having to completely drain a hot water tank just to fill it up.
  • Low Operating Costs – A huge advantage of a tankless system, also referred to as an on-demand system, is that using it can save money on water often cutting your water heating costs by as much as 34% annually. Sure you'll pay more up front but you'll recover that money over time.
  • Space Requirement – Tankless systems can be placed in more locations than a tank system, including on attic rafters, in a crawlspace or on the exterior of the dwelling. Adding a small under sink water heater to your kitchen is a great way to save both time and money.
  • Lifespan – Tankless units tend to last almost twice as long, or up to about 20 years, and have fewer components that can fail.
  • Almost Maintenance Free – Other than descaling a tankless water heater every 1-2 years, there's not much more as far as maintenance is concerned.


  • Upfront Cost – Cost is the most prohibitive factor for tankless water heater. With prices generally ranging upwards of $1,500, buying one on impulse can be a big blow to your budget. A condensing tankless water heater will generally be more expensive than a non-condensing unit.
  • Installation – A tankless system is not immediately compatible with a traditional system, so installation (or upgrading from a tank system) is more difficult and costly.
  • Simultaneous Use – Larger families may also need to consider if a tankless model can keep up with the demands of simultaneous users. There's a limit to the amount of water a tankless model can heat at one time so if two people are taking showers in two different bathrooms and the dishwasher is also running, there may not be enough hot water for everyone if the unit's gallons-per-minute rating is not high enough.

For more information, see our Tankless Water Heater Buying Guide.

author avatar
Anthony Barnes
Anthony Barnes is the founder of Water Heater Hub and a second-generation plumber by profession. Before developing Water Heater Hub, Anthony Barnes was a full-time plumber, and he has undertaken a wide variety of projects over the decades. As a second-generation plumber, it was easy for Anthony to get used to the technicalities of all from a tender age


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