06 Oct Instantaneous Hot Water Systems in Brisbane Explained
I get asked about instantaneous hot water systems most weeks, usually by someone who’s sick of running out of hot water halfway through a shower, or a café owner who’s had a continuous flow unit die on them in the middle of a Saturday morning rush. Between residential homes and commercial kitchens across Brisbane, I’ve installed and repaired more of these units than I can count. Here’s what an instantaneous system actually is, how it compares to a storage tank, and whether one makes sense for your home or your business.
What is an instantaneous hot water system?
An instantaneous hot water system, sometimes called continuous flow or tankless, heats water as it passes through the unit rather than storing a tank of hot water ready to go. Turn on a tap, the unit fires up, and water is heated on demand as it flows through. There’s no tank sitting there losing heat overnight, and in theory you don’t run out of hot water, because it keeps heating for as long as the tap stays open and the gas or power supply can keep up.
The trade-off is that the unit has to be sized properly for how much hot water you’ll pull at once. Run two showers and a kitchen tap at the same time on an undersized unit and you’ll notice the temperature drop, which is the single most common complaint I hear about instantaneous systems that were never sized right in the first place.
Gas or electric?
Most of the instantaneous systems I install in Brisbane homes run on natural gas or LPG, because gas units heat water faster and handle higher simultaneous demand without the hefty electrical upgrade an equivalent electric unit often needs. Electric instantaneous units exist and suit smaller, specific jobs well, like a single bathroom or an under-sink point, but trying to run a whole house off electric continuous flow usually means a single-phase to three-phase upgrade that adds real cost to the job.
For a typical Brisbane household, I’ll usually recommend a gas continuous flow system sized to the number of bathrooms and simultaneous outlets you actually use, not just the number you have. For a commercial kitchen or a multi-outlet setup, gas is almost always the more practical choice.
Good for homes, essential for a lot of businesses
For residential customers, the appeal is straightforward: no 30-minute wait for the tank to reheat after a big family shower run, and no wasted energy keeping a full tank hot all day when half the house is at work. It suits larger households and homes that go through a lot of hot water in short bursts, like busy mornings before school and work.
For commercial and hospitality clients, an instantaneous hot water system or continuous flow often isn’t a nice-to-have, it’s the only setup that actually works. A café running a coffee machine, a dishwasher and a hand basin at the same time all day needs hot water that doesn’t run out, and a storage tank sized for that kind of continuous demand would need to be enormous. We’ve set up continuous flow systems for cafés, restaurants and commercial kitchens across Brisbane, and it’s also a common fit in aged care and medical facilities where hygiene requirements mean hot water demand is constant and can’t afford gaps.
What it actually costs to run and install
Running costs tend to come out roughly even with a well-maintained storage system over time, the main saving with instantaneous units is not heating water you’re not using, rather than a dramatic cut in your gas bill. Installation cost depends heavily on gas line sizing, venue access, and whether an existing storage system needs to be removed, so it’s genuinely a quote-by-quote job rather than a one-size price. If you want the fuller cost breakdown, I’ve written up a separate guide on hot water system installation costs in Brisbane ( /hot-water-system-installation-cost-brisbane/) that covers instantaneous, storage, electric, gas and heat pump options side by side.
Is an instantaneous system right for you?
If you’ve got a smaller household, a single bathroom, or you’re genuinely happy with your current storage tank, there’s no pressing need to switch, a well-maintained storage system does the job perfectly well for plenty of homes. Where instantaneous systems earn their keep is larger households, renovations where you’re reconfiguring the hot water setup anyway, and any commercial or hospitality site where hot water simply can’t run out partway through service. Because we’re licensed for both plumbing and gas fitting, we handle the whole job ourselves, pipework, gas connection and compliance, with one team and one visit.
Thinking about switching to an instantaneous hot water system, for your home or your business? Call Alexander Gas & Plumbing Co on 0404 823 184 or (07) 3375 4445, we’re licensed for both the plumbing and the gas fitting side of the job, so it’s one team from quote to commissioning.
Here’s a couple of good resources to continue your own research:
Hot water systems (Your Home, Australian Government)
Energy Rating (Australian Government)
Frequently asked questions about Instantaneous Hot Water Systems
How long do instantaneous hot water systems last?
Most good-quality gas continuous flow units last around 15 to 20 years with regular servicing, similar to a gas storage system, though that depends on water quality and how well it’s maintained.
Can an instantaneous system run two showers at once?
Yes, provided it’s sized correctly for simultaneous use. This is exactly where undersized units fall over, so getting the sizing right at installation is the most important part of the job.
Is an instantaneous hot water system cheaper to run than a storage tank?
Generally a little cheaper over time, since you’re not keeping a full tank hot around the clock, but it’s not usually a dramatic saving. The bigger benefit for most households is not running out of hot water.
Do commercial kitchens need a bigger unit than a house?
Usually, yes. A café or commercial kitchen running multiple hot water outlets at once needs a unit, or sometimes multiple units, sized for that continuous commercial demand, which is a different calculation to a residential job.
Can you install an instantaneous hot water system if I currently have a storage tank?
In most cases, yes. We’ll assess your existing gas line, hot water demand and plumbing layout to confirm what’s involved before quoting, since every property’s setup is a little different.
With over 30 years in the plumbing industry he provides a level headed and experience approach to all client related work.He is genuine person with a keen interest in family, friends and helping others.
He holds Queensland Plumbing Licence 28840, Gas Licence L31 902, QBCC License 12 654 79, and Building Assets and Services Contractor licence 860 066.
Rich believes in educating clients about their plumbing systems and providing honest advice about when professional help is needed.
He founded Alexander Gas and Plumbing Co in 2013 to provide personal, trustworthy service to Brisbane families and businesses.
- Instantaneous Hot Water Systems in Brisbane Explained - 6 October 2026
- How To Clear A Blocked Drain In Brisbane - 17 September 2026
- Is Solar Hot Water Worth It in Brisbane? - 9 September 2026
No Comments