Tankless vs. Traditional Water Heaters: A Plumber’s Full Comparison

Your water heater can be both a burden and a blessing, depending on your chosen type and how it fits your home. From steep energy bills to frequent repairs, you’re likely to shoulder these consequences if you’re relying on an inappropriate unit.

Here’s the thing: you only have two choices. Either you stick with a tank system or a tankless one. The choice may be simple, but both units have distinct advantages and drawbacks. Today, we’ll walk you through those aspects to help you pick what’s right for you.

How Do They Work?

Let’s begin with the basics. Traditional water heaters store water in a tank. That tank is usually somewhere between 30 and 80 gallons. The unit keeps that water hot all the time, so it is ready when you need it. Once the tank runs out, you need to wait for it to refill and reheat.

Tankless water heaters, on the other hand, work a little differently. There is no tank. Instead, water passes through a small unit that heats it instantly. You get hot water on demand, without waiting for a tank to fill back up. It is a smart system, and it works well if sized correctly for your household.

Space Saving

A water heater’s size is enough for many homeowners to decide which one is best for their home. The difference in size is a major differentiator here. If your home lacks the space to cater to bulky tanks, a tankless water heater is your clear choice.

Some units can be as small as a 13-inch laptop, although thicker (obviously). They are those mini electric tankless units that are roughly 10–12 inches tall, 6–8 inches wide, and 3–5 inches thick. These units can be installed in your sink cabinet, closet, or wall-mounted outdoors. In contrast, the average traditional water heater (50 gallons) can be as big as a small refrigerator or a large trash can. This is a significant space-eater in any space, whether in your garage or basement. Obviously, a more compact unit is a better choice here.

Winner: Tankless water heater

Installation

You may think that tankless water heaters are easier to install, given their compact build. But it’s actually the opposite. It’s mainly because these units require upgrading your home’s plumbing, electrical system, and gas lines (for gas-powered units). There’s also the need for more accurate venting and wall mounting, adding to a more complex layout.

On the other hand, traditional water heaters don’t require as much. Especially if you’re just swapping your old tank with a new one, there are virtually no major changes needed. While you still need to comply with local codes and safety rules, upgrading your plumbing, electrical system, or gas lines is unnecessary.

Winner: Traditional water heater

Energy Use and Efficiency

Did you know your water heater is your home’s second-highest energy consumer? It trails behind your HVAC system. But between the two, there’s one that can really inflate your water bills—traditional water heaters.

They are constantly heating a huge reserve of water, even when you’re not using your tap. This means higher standby energy loss. This is not an issue with tankless units that only heat water on demand. As a result, they can be up to 34% more efficient than tank systems.

Winner: Tankless water heater

Hot Water Supply

This area can be a tricky one. Traditional tank water heaters store a set amount of hot water, usually 40 to 80 gallons. Once that’s used up, you’ll have to wait for the tank to refill and reheat. This can be a dealbreaker for larger families or back-to-back showers.

Tankless systems heat water as you need it, which means unlimited hot water, but only up to a point. If multiple fixtures run at once (like two showers and a dishwasher), the flow rate can drop, especially on smaller units.

If you want continuous hot water all day but don’t usually have everyone showering at once, tankless wins. But if your household uses a lot of hot water at the same time, a traditional tank may keep up better, or consider installing multiple tankless units.

Winner: Tie – depends on household size and usage patterns

Lifespan and Maintenance

In any appliance, lifespan and maintenance needs are major considerations. Between tankless and traditional water heaters, the gap is significant.

Tankless water heaters generally last longer, up to 20 years or more, with strict maintenance. They also have replaceable parts, so you don’t have to scrap the whole unit if something breaks. However, they do need regular descaling, especially in hard water areas.

Traditional tanks have a lifespan of 8 to 12 years, almost twice as short as that of their counterparts. They’re simpler, but once the tank starts rusting or leaking, it’s usually game over. They also need periodic flushing to remove sediment buildup, but many homeowners skip this step, shortening the unit’s life.

Winner: Tankless water heater

Upfront Costs vs Long-Term Value

Let’s be real, tankless water heaters cost more upfront. Between the unit itself and the installation, you could spend twice as much as a traditional tank setup.

But that investment pays off. Tankless systems are more energy-efficient, last longer, and can reduce utility bills over time. Depending on your hot water usage, the long-term savings can outweigh the initial expense.

Traditional water heaters are cheaper to install and great for tight budgets. But they’ll cost more in the long run due to higher energy use and shorter lifespan.

Winner: Tankless water heater (long-term); Traditional (short-term budget)

What Is Best for Your Home?

There is no one-size-fits-all answer here. A tankless water heater is a great choice if you have limited space, want to save energy, and do not mind a higher initial cost. It is also ideal for households that use hot water throughout the day rather than all at once.

Traditional water heaters are still a solid pick. They work well in larger households where hot water demand happens all at once. They are also easier and cheaper to install, especially in older homes with existing setups.

If you are not sure which way to go, talk to a plumber. A quick look at your home’s layout and your family’s water habits can help make the choice a lot easier.

Get the Right Water Heater Without the Guesswork with Streamline Plumbing

Choosing between a tankless or traditional water heater isn’t always easy, but you don’t have to figure it out alone. Whether you’re dealing with rising energy bills, running out of hot water, or planning a home upgrade, Streamline Plumbing is here to help.

We offer honest advice, expert installation, and fast plumbing service you can count on. Our licensed plumbers will guide you to the best option for your space, budget, and lifestyle, without the pressure.

Call Streamline Plumbing today, or book your schedule online!