When a client calls me to replace their water heater, it's almost always the same question: "should I switch to tankless?" The ads are everywhere, the salespeople are convincing, the promised savings are appealing. But before you sign for an on-demand unit that costs two to three times more up front, you need to understand what nobody says clearly.
In this article I'll give you the honest opinion of a plumber who has mostly installed tank models in Quebec, and who knows why. No disguised sales pitch. Just the facts, the real advantages of both options, and above all the drawbacks people discover far too often after the purchase.
The two technologies, briefly
The conventional water heater (tank model) is the technology we all know: a 40, 60 or 80 gallon tank that heats water continuously so it's ready at any moment. When you open a hot tap, water leaves the tank, and the tank refills while the element keeps heating.
The tankless water heater (on-demand) is a compact unit that heats water as you call for it. No tank. When you open the tap, cold water passes through a heat exchanger that warms it instantly.
On paper, tankless looks like the logical evolution. In practice, it's more nuanced.
The real advantages of a conventional water heater
After more than 12 years installing them, here's why the tank model remains an excellent choice for most households:
Lower purchase price. A residential tank water heater runs from a few hundred dollars to around $1,200 depending on capacity and brand. An equivalent tankless unit? Often two to three times more, and that's before we even talk about installation.
Simpler, faster installation. Your connections are already there, your electrical supply is sized for it, and the swap generally takes a few hours. No need to modify your home's systems.
Known reliability, proven technology. These units have been on the market for decades. We know exactly how they age, when they cause trouble, how to diagnose them. Replacement parts are available everywhere. No mystery.
Affordable replacement cost. When your tank model reaches the end of its life, replacing it costs a fraction of a new tankless unit. It's a predictable expense.
Suits every household. Whether you live alone, as a couple, or as a family with four kids, there's a tank capacity that fits. No need to calculate peak flow rates or simultaneous showers.
The drawbacks of a tank model you should know
Let's be honest — it's not all upside:
A lifespan of roughly 10 to 12 years. Beyond that, the risk of leaking rises significantly. The tank, slowly corroding from the inside, eventually perforates. It's rarely dramatic, but it is inevitable.
Ongoing energy cost. Even when nobody is using hot water, the heater keeps the tank up to temperature. That's what we call standby loss. Over a year, it represents a non-trivial share of your bill.
It takes up space. A 60 gallon tank is a cylinder roughly 5 feet tall and 2 feet across. In a small apartment or a condo, that's a real space trade-off.
Hot water limited by capacity. If you fill a large bathtub while someone else showers, you can hit the tank's limit and end up with cold water. Recovery time depends on the heating capacity.
The real advantages of tankless
Now the other side of the coin. Tankless has genuine advantages, and they deserve honest recognition:
Unlimited hot water. As long as you have the supply (gas or electric), hot water keeps coming. You can take a 45-minute shower without fearing the cold. For certain households, that's real comfort.
Long-term energy savings. No standby losses — water only heats when you use it. Over 15 to 20 years, that adds up to real savings, especially if you use little hot water day to day.
Longer lifespan. A well-maintained tankless unit can last 20 years or more, nearly double a tank model. You replace it less often.
Space savings. The unit is compact and often wall-mounted. You get back the space your tank occupied, which can matter in a small home or free up part of a basement.
The tankless drawbacks salespeople won't tell you about
This is where the conversation gets honest. Here's what I see in the field:
1. Much higher purchase and installation cost
We're often talking double or triple the price of an equivalent tank model, before installation. And the installation itself is more complex: you often need to add a dedicated electrical line (sometimes high-capacity 240 V), modify the venting for gas models, and adapt the plumbing. That can easily double the total bill.
2. Limited flow when several taps run at once
Contrary to what people assume, a tankless unit isn't magic. It has a maximum flow rate. If you're showering while your partner does dishes and the washing machine is running, the hot water flow gets divided, and the temperature can drop. For large families, you often need a more powerful unit (and a more expensive one), or even several units in parallel.
3. More demanding maintenance
This is what you might call the fine print. A tankless unit needs an annual descaling to keep its performance. That's an extra service, it has to be done by a professional, and it adds a recurring cost. Neglect the maintenance and you shorten the lifespan and lose efficiency.
4. Quebec water and scale — the invisible trap
This is the point salespeople systematically forget to mention, and it's probably the most important one for you if you live on the South Shore or anywhere else in Quebec. Water in several Quebec regions contains minerals that form scale (limescale) when heated.
In a conventional water heater, the scale settles at the bottom of the tank. You can tolerate it for years — it slightly reduces efficiency, but it doesn't kill the appliance.
In a tankless unit, it's completely different. Water passes through a narrow, hot heat exchanger. Scale builds up there quickly, blocks the channels, reduces flow, and eventually damages the unit. Without water treatment or regular descaling, we see tankless units lose a great deal of their performance, or fail outright within a few years.
Plenty of my clients who went tankless without installing a water softener first have had unpleasant surprises. Before you buy, you either treat the water, commit to rigorous maintenance, or choose a different technology.
5. Higher repair costs
The components of a tankless unit (heat exchanger, control electronics, sensors) are expensive to replace. A single repair can represent a significant share of the price of a new appliance. You don't have the same financial flexibility you'd have with a tank model.
So which one should you choose?
Here's my honest opinion after years of installations.
The conventional water heater remains the right choice for most Quebec households. It's affordable, reliable, predictable, suited to our water, and easy to maintain. Unless you have a particular need or a comfortable budget, it's rarely a mistake.
Tankless becomes relevant in specific cases:
- You have a comfortable budget for the initial investment
- You live in a small space where reclaiming the floor area genuinely matters
- You're prepared to install a water softener or treatment system
- You accept the commitment of an annual professional descaling
- You plan to stay in the home long enough to recoup the investment (15–20 years)
If you check several of those boxes, tankless can be an excellent investment. Otherwise, a tank model remains a solid, sensible choice.
My last piece of advice
Before you decide, get advice from a plumber who has no commercial interest in selling you a particular brand. Many tankless advocates are in fact distributors for specific brands, and their advice is skewed by their margin.
An independent plumber can assess your actual usage, your water, your setup, and recommend the best option for your situation specifically.
Thinking about replacing your water heater? I'm available across the South Shore to assess your situation and give you honest advice. Call me at 263-382-8612 or request a free quote.