Tank vs Tankless. Which is the best water heating system?

Should I get a tankless water heating unit, or install a hot water tank system?

When your current water heating system breaks – or if it has just broken – you’re going to have to think about a replacement. And usually, many people just say – “we’ll get what we got last time”. But some people, like yourself, choose to research this issue, and those that do tend to discover there are many, many factors at play.

This decision isn’t easy, as every household is different. If you’re looking for the short answer, skip down to the very ending of this article – you’ll find it there. But if you are here to read up on this topic and do your research, we strongly recommend you peruse the article, and not just glance through it.

The decision could either save you thousands or cost you thousands, and if you’re somebody who is tight on finance – like most of the population – that choice will matter, and it will matter greatly.

Both options have their positives, and both options also have their negatives. That’s not to say they’re perfectly balanced, though. Whilst we will try to balance the pros and the cons of each, and discuss the features (or lack of features) on each type, not all of these issues will apply to every household.

Therefore, it is up to you to decide which the best option is for you. We’ll kick of this article with a brief description of how each of these system works, what it’s made of, and how long you can expect the system to last. We’ll also chuck in some brief “pros and cons” for each, and then we’ll follow that all up with what we recommend for your own situation.

Again, as already has been said, this really can be a difficult decision to reach, as it will unavoidably impact your finances in the long run. With that said, let’s move onto the workings of a traditional, tank-based water heating unit.

The Traditional, Hot Water Tank System – How it works and its pros and its cons

Let’s firstly talk about what a hot water tank system actually is. This is a sort of “evolved” version if you like of a simply pot on a stove. You put the water in a pot (the tank), and ignite a fire beneath it (this hasn’t changed, you still stick a fire beneath the unit) to heat it up. From there on, hot water flows to any outlet that demands it. And that, is how a tank-based water system or unit works. It’s not a very complicated setup, only using basic, traditional methods for heating water.

We’ve accidentally covered how the actual tank works! So, let’s move onto the pros of a traditional, hot water tank based system or unit to deliver hot water to you and or your family.


This system is traditional because it works. The fact it has survived for so many hundreds of years says a lot about its reliability and ease of use. And yes, these systems, whilst they may certainly have been slightly less advanced than they are in today’s world, have certainly served generations of families without inconvenience.

And that’s fantastic – you know this system is reliable if it’s lasted this long.

A hot water heating system based on the tank model is certainly much cheaper to buy, too – and if you’ve already had one before (or yours has just broken down) then it won’t cost you much (if it will cost you anything but a few minutes) to install in your home.

They’re highly replaceable when they do break, and work a charm when installed properly.

Another huge advantage of the hot water tank heating system or unit is that no matter what the rate of flow in your property, every single tap and outlet can receive hot water on demand, as there will always be hot water in the tank, provided it has access to the main access to your home. And this is a huge advantage over tankless water heaters, where you can literally just run out of hot water if too many people are using outlets at once.

Therefore, when it comes to a tanked solution, this may be ideal for your household in certain circumstances – and we shall cover these later on in the tank-based system section.

Now, to move on to the cons!


A system that heats water via a large tank is incredibly inefficient, and not even salesmen will deny that. A tankless option is significantly more efficient than a traditional hot water tank heating system. But why does this happen?

When you consider what a tank hot water system actually is, you’ll find that it’s inefficient in its own design. You’re heating a lot of water at once, and you don’t even know if you’re going to be using that water anytime soon. And, in modern heaters, if that water ends up cooling down (which it unfortunately does quite often), you’re going to have to expend energy re-heating all of that water until you use it, at which point it will re-fill and the process will begin all over again.

This is a major disadvantage of hot water tank systems. They don’t really take any notice of whether you actually intend to use hot water or not, and just heat it anyway. Not only can this be slightly costly in the short run, but over the course of a holiday when you’re not even at home to use your hot water, this can be even more expensive – and expensive for no reason.

Hot water tank systems or units must also be very regularly replaced. Every ten or so years, you might discover internal leakage, a rupture or system failure. When compared with tankless water heaters, where some manufacturers boast over thirty years of life and usage, this system might even be called absolutely terrible.

The Modern, More Efficient System; The Tankless Water Heating System – How it works, along with its pros and its cons

The more modern water heating system is the tankless water heating system. It provides instant hot water to families, and only uses energy when hot water is needed, unlike a hot water tank which is constantly heating water no matter if it is necessary or not.

It works by talking cold water from its cold-water inlet – the mains – and running it through a coil of pipe, that is either surrounded by a roaring hot flame, or an electrical heating element. This instantly raises the temperature of the water, and then forces it out at high pressure to the outlet where the hot water is demanded. Let’s move onto the pros and the cons.


I mean, the pros really are quite obvious. The first is that you always have access to hot water, and instantly too. There’s no waiting on a tank to fill up, only switching on your hot water, and it’s there. And there’s no limit to how much you can use in a day, provided the system you purchase is capable of a high rate of flow.

You’ll also save on a lot of space. A tank can take up a few cubic meters of space in your room. For this reason, a tankless water heater might be better for you, especially if you’re paying for third party storage solutions.

Not only will you save on space and energy, but in the long run you’ll save on a lot of money with a tankless water heating system. Your bills will be much lower on a monthly basis.

All in all, it’s a great option if you can afford the high upfront cost, described in the cons.


There’s a lot of pros, but there’s also quite a few cons, starting out with the fact that not every home is compatible with what a tankless water heater demands.

Sometimes, you’ll end up having to re-wire your entire gas system at home only to fit a tankless water heater.

They’re also quite expensive upfront.

That considered, there really aren’t that many cons.


If you’re a cash-strapped family, and you have already had a tank-based water heating system or unit, you’re very likely going to benefit from staying with it, as installing a tankless water heater may be incredibly expensive – especially if your gas lines aren’t in the correct position.

However, if you can afford the cost of a tankless water heating system, you should absolutely go for it. It will save you money in the long run, and last a lot longer than a tank-based water heating system.

So the very final verdict? Well, it entirely depends on you, your family, and your financial situation, as well as how your home was built originally.

About the author

Steve Bates

Hi, I'm Steve and I currently reside in Chicago, Illinois. Although for most of the last 20 years I was a partner in a HVAC company down in Austin, Texas.

I understand the frustration involved with dealing with water heater repairs and replacing or upgrading to a new, more efficient model.

My aim is offer some basic advice on fixing home hot water systems. And if a repair isn't possible, then to make the process of selecting a new water heater – be it gas or electric - as simple as possible.

So that you can save money and have a safe and reliable hot water system in your home for many years to come.