Repaired where a repair is honest and replaced where it is not, and sized for the number of households a house holds now rather than the one it was built for.
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A great many houses across this region are no longer one dwelling. Terraces have been split into flats, rear additions have become self-contained, and a house built for one family now holds two households. The hot water system is usually the one that was there before all of that.
The complaint that follows is always the same: it never lasts. And the instinct is always the same too: the system must be faulty. Usually it is not. It is doing exactly what it was designed to do for a household that no longer lives there.
The reason is timing rather than headcount. Four people in one household stagger without thinking about it, because they know each other's routines and they can hear the shower. Two separate households have no reason to coordinate and no way to. So the demand stacks into the same window instead of spreading across the morning, and a tank that is perfectly healthy empties.
That opens up more options than buying something bigger. A faster recovering unit, or continuous flow which cannot run out at all, or in some cases separating the supplies so each dwelling has its own system and its own running cost. That last one frequently solves the argument as well as the hot water.
Say so when you ring. It changes the diagnosis from a fault to a sizing conversation, and those cost very different amounts.
A house divided into two dwellings usually keeps the hot water it already had. Nobody installs a second system as part of a conversion unless somebody insists on it.
So the unit sized for one household in 1975 is now serving two, and it is doing exactly what it was always able to do.
That is the whole of the problem. The system has not failed. The demand on it has changed.
One family spreads demand without thinking about it. People wait, people go later, somebody showers at night. It happens without anybody organising it.
Two households have no reason to coordinate and no easy way to. Both leave for work at similar times and both want hot water in the same forty minutes.
So the same total number of showers arrives in a much narrower window, which is a completely different demand on a tank.
Capacity is drawn down by what is taken in the same forty minutes rather than by what is taken in a day. A cylinder in perfect condition will run out if the draw is concentrated enough.
Which is why replacing a working unit frequently disappoints. The new one has the same capacity problem as the old one.
Recovery rate matters as much as volume here. How fast it reheats decides whether the second household gets anything.
Two systems means two running costs, which is frequently the real friction rather than the temperature of the water.
One meter and one bill for two households is an arrangement that produces arguments regardless of how well the plumbing works.
So on a property that is genuinely two dwellings, separating the hot water is worth pricing even where the existing unit is coping.
A second unit, its own supply, and pipework to serve one dwelling independently of the other. Where and whether that fits is the whole question.
In this housing the constraints are space, an external wall for a flue if it is gas, and getting pipe from a new unit to the fixtures it serves without opening every wall.
It is a real job rather than a swap, and it is worth quoting properly rather than estimating.
It stores nothing, so there is no volume to exhaust and no such thing as a second household arriving too late. It heats on demand for as long as demand lasts.
The trade is that it needs an external wall, a flue position with the required clearances, and gas capacity, and on a terrace those are genuine constraints rather than details.
Where it fits, it is frequently the cleanest answer to this specific problem.
Capacity is decided by how many people shower in the same window. On a split property that number is the sum of two households behaving independently.
So describe the actual arrangement when you ask for advice, including how many people and roughly when. That is the number the sizing runs on.
A recommendation made without it is a guess with a price on it.
A shower draws hot and cold together, so the head sets the rate at which a cylinder is drawn down. Anything installed before the WELS labelling scheme can flow well above nine litres a minute.
On a split property with old fixtures, changing two heads occasionally solves the whole complaint for a fraction of the cost of anything else on this page.
If it does not, you have lost very little and you know the problem is genuinely capacity.
Almost entirely because of the anode. It corrodes on purpose, protecting the steel, and when it is spent the tank starts consuming itself instead.
Scale is not the issue in Sydney. The supply is soft, so a tank here does not silt up the way one in a hard-water region does.
That is why age alone tells you very little. A cylinder can be sound at fifteen years or finished at eight, depending on whether anybody ever looked.
Water emerging from the body of the cylinder rather than from a fitting on it. That is the steel, and steel does not get patched.
A leak at a valve or a connection is ordinary work and frequently cheap. Confusing the two costs people a great deal.
Isolate it, cut its power or gas, and book the replacement. Waiting adds flooring and plaster to a bill that was only ever going to be a hot water system.
The usual comparison is capacity and running cost. On a house holding two households the question is different: what happens when the demand arrives all at once.
| Type | How it behaves when demand stacks | Expected span | Worth considering when |
|---|---|---|---|
| Electric storage | Empties, then recovers slowly | About 8 to 12 years | Demand genuinely does spread across the day |
| Gas storage | Empties, but recovers noticeably faster | About 8 to 12 years | Gas is connected and mornings are the pinch point |
| Continuous flow | Cannot empty, because nothing is stored | About 15 to 20 years | Running out is the actual complaint |
| Heat pump | Empties, moderate recovery, cheapest electric to run | About 10 to 15 years | There is outdoor space with genuine airflow |
| Two separate systems | Each household limited only by its own use | As per the type chosen | The running cost is as much the issue as the hot water |
Count the people who want hot water inside the same hour, and count separate households as though they will overlap, because they will.
| Occupants | Electric storage | Gas storage | Continuous flow |
|---|---|---|---|
| One or two | 125 to 160 L | 90 to 135 L | 16 L/min |
| Three to four | 250 to 315 L | 135 to 170 L | 20 L/min |
| Five or more | 315 to 400 L | 170 L or twin | 26 L/min |
| Two separate households | Size up a step | Size up a step | 26 L/min |
Fixed price agreed before anything starts. These are indicative 2026 ranges.
Comes straight off the repair if you tell us to go ahead.
Two parts account for the overwhelming majority of electric failures.
Buys years on a cylinder that is otherwise sound.
One number covering the appliance, fitting it, and removing the old one.
Where two dwellings would be better with their own system and their own bill.
Hot water outweighs everything else in the callout diary. Across this region that means a great deal of electric storage in the older housing, gas wherever a property is connected for it, and continuous flow where a cylinder had to leave the floor. These are the makes.
We service and replace these systems as an independent licensed plumber. We are not an agent for, or endorsed by, any of these manufacturers.
Type and age of the unit, and how many separate households draw on it. That last one is the question nobody expects.
Every unit carries a compliance plate with a date, and we read it out, because a real age turns repair or replace into arithmetic.
Anode, element or thermostat where that solves it. A changeover only where the unit is genuinely finished or genuinely too small.
We run it, check the delivered temperature, take the old unit away and leave you the paperwork.
A licensed plumber answers directly. Repairs are usually same-day and plenty of changeovers are too.
Call 1300 381 569Frequently not. It is far more often a system doing exactly what it was designed to do for a household that no longer exists. A storage unit sized for one family with one morning routine is being asked to serve two households with two, and two households do not coordinate their showers.
Because of timing. Four people in one household tend to stagger, because they know about each other. Two separate households have no reason to, so peak demand doubles up rather than spreading out. The tank does not care how many people there are, it cares how much is drawn in the same forty minutes.
Sometimes. The options are more interesting than that though: a larger unit, a faster recovering one, a continuous flow system that cannot run out at all, or in some cases separating the supplies so each dwelling has its own. Which is right depends on the property and on what the two households actually want.
Sometimes, and it is worth asking about because it also separates the running cost, which is frequently the real source of the friction. Whether it is possible depends on space, on the fuel available, and on what the building will allow, and that is a look rather than a phone answer.
Soft water is why they fail this particular way. In hard-water places a tank silts up with scale. Sydney's is not like that, so the sacrificial anode is consumed protecting the steel and the tank starts corroding once it is gone, or an element burns out. Both are frequently repairs.
Replace. Water from the body of the cylinder means the steel has gone and there is no patch for that. Shut it off and ring, because the damage compounds daily.
Diagnosis is $120 to $250 and comes off the repair. An element or thermostat is $250 to $550. An anode is $300 to $600. A storage replacement is $1,400 to $2,800, and a continuous flow changeover $2,000 to $3,800.
Tell us the type, roughly the age, and how many separate households use it. Those three answers settle most of it before anybody drives anywhere.
Kept if it can be kept, replaced if it cannot, and sized for the house as it is now.
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