On tank supply we check the pump and the inlet filters before we blame the heater. A continuous flow unit that will not stay lit is very often being starved of flow rather than failing.
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A water heater can only work with what arrives at it. On pump-fed supply, a good deal of what looks like a failing heater is actually a supply problem, and replacing the heater fixes nothing.
The clearest example is a continuous flow gas unit. It will not fire until enough water is genuinely moving through it, and it needs that flow held to keep firing. A pressure pump that has weakened over the years, or one that was undersized for a long run to begin with, sits close to that threshold. The unit lights, the flow sags, it drops out, and the shower goes cold and back again. That is a supply fault reading as a heater fault.
The other one is the inlet filter. Rainwater carries fine sediment and grit that town water does not, and it collects in the screens on the way in. A restricted filter produces exactly the same lukewarm behaviour, and it is a maintenance item almost nobody is told about at installation.
Then there is the valve problem, which applies everywhere but bites here too. A failed pressure limiting valve leaves a storage tank running at a pressure it was never rated for, the relief valve weeps to cope, and a unit good for a decade gives you six or seven years.
On tank supply, say so when you ring. That symptom points upstream of the heater far more often than at it, and it is worth checking before anyone quotes a replacement.
An instantaneous gas heater has a minimum activation flow rate. Below it the unit does not fire at all, and you get cold water rather than a weak hot stream.
On a pump-fed rainwater supply that threshold is a real consideration, because a pump delivering marginal flow can leave a continuous flow unit unable to start.
So on tank water the supply and the appliance have to be matched deliberately rather than assumed compatible.
Rainwater arrives with fine sediment, grit and organic matter that town water does not carry, and the filters that catch it need cleaning rather than ignoring.
A blocked inlet filter reduces flow, which on a continuous flow unit can drop it below the activation threshold and produce a no-hot-water call.
It is a five minute check and it is the first thing worth doing before ringing anybody on a tank property.
A pressure limiting valve holds the incoming supply down to what the cylinder and the fixtures are built for, and it wears out at around eight to twelve years.
It fails open, so nothing warns you, and the tank and every fitting in the house then spend their days working above what they were designed for.
On a pump-fed system the pump's own pressure setting matters in the same way, and it is worth checking rather than assuming.
Minerals and particles settle in the bottom of a storage cylinder, and on tank water there is more of both arriving than there would be on town supply.
That layer takes up volume the tank used to hold and it sits between the heat source and the water, so the unit works harder for less.
The rumbling on heating that people notice is water trapped under that layer boiling its way out.
Every storage tank carries a sacrificial anode that corrodes deliberately so the steel does not. When it is used up, the tank begins corroding instead.
Discoloured hot water with clear cold is that process becoming visible, and it can only be coming from inside the cylinder.
It is the clearest early warning a tank gives, and on a property where a same-day replacement is not guaranteed it is worth acting on.
On a large block the unit can sit a considerable distance from the furthest outlet, and the water standing in that run has to be pushed out before hot arrives.
That is geometry rather than a fault, and no new unit shortens it. Insulating the run helps at the margins.
A second small unit at the far end is the other honest answer, and on acreage it is frequently the cheaper of the two.
The compliance plate carries the date. Under about eight years a failure is usually a part. Past twelve the tank lining is generally the issue and a replacement is honest.
Photograph the plate and send it through before anybody attends, because out here a second trip is a long drive for both of us.
On tank water, mention that too, because it changes what we check first.
A tank that empties mid-shower is generally undersized for how the household now behaves rather than faulty, and sediment loss of volume compounds it on rainwater supply.
Capacity is drawn down by what is taken in the same short window, and households change on that measure without the building changing.
Describe your actual mornings when you ask for advice, because that is what the sizing runs on.
A shower draws hot and cold together, so the head sets the rate the cylinder is drawn down at. Older heads can flow well above nine litres a minute.
On tank water it also reduces how much you are drawing from a finite supply, which matters in a dry stretch.
A pair of heads costs a fraction of a hot water system and takes minutes to fit.
Close the water at the unit, turn off its electricity or gas, and ring. Those three things, in that order, and then the replacement can be arranged at a sensible pace.
Water coming from the cylinder body is the end of that unit. The steel has gone and no repair returns it.
The reason for speed is not the tank, which is already finished. It is the floor, the wall and anything below it.
On acreage two things narrow the field before anyone talks about running cost: whether mains gas reaches the property at all, and whether the water arrives under mains pressure or from a pump.
Space is rarely the constraint here that it is closer to the city, which makes heat pumps and solar genuinely practical. Flow rate is the constraint instead, and it is the one worth establishing before choosing anything instantaneous.
| System | How it heats | Typical life | Suits |
|---|---|---|---|
| Electric storage | An element heats a tank, often overnight on a controlled load tariff | 8 to 12 years | Pump-fed properties, because a tank is far less flow-sensitive |
| Gas storage | A burner under the tank, reheating through the day | 8 to 12 years | Properties with mains gas or a well-sized LPG installation |
| Continuous flow | Heats on demand, so there is no tank to run out | 15 to 20 years | Mains pressure. On a pump, confirm the flow rate first |
| Heat pump | Moves heat from the surrounding air, like a fridge in reverse | 10 to 15 years | Acreage, where siting one is easy. Efficiency dips on cold mornings |
| Solar with boost | Roof collectors with electric or gas backup | 15 to 20 years | Open north-facing roof, which rural blocks usually have |
A starting point rather than a rule. A household showering back to back within an hour needs more than the same number spread across a morning.
| People in the home | Electric storage | Gas storage | Continuous flow |
|---|---|---|---|
| 1 to 2 | 125 L | 135 L | 16 to 20 L/min |
| 3 to 4 | 160 to 250 L | 135 to 170 L | 20 to 26 L/min |
| 5 or more | 250 to 315 L | 170 L or more | 26 to 32 L/min |
Fixed price agreed before anything starts. Indicative 2026 Sydney ranges for guidance, not quotes. On pump-fed supply the pump and filter check is part of the diagnosis rather than an extra line, because otherwise you risk paying for the wrong repair.
The fault identified, including supply and pump where the property is tank-fed.
Elements, thermostats, relief valves and pressure limiting valves.
Supplied, installed and the old unit taken away. Priced on capacity.
Including the gas work and the compliance certificate. Sized against actual flow.
Before any rebate you qualify for. We will tell you what is currently available.
Almost every home here runs one of these eight. Rheem, Vulcan and AquaMAX storage tanks are what we mostly find on the older properties, plenty of them on a second or third replacement, and a storage tank remains a sensible choice on pump-fed supply because it is far less sensitive to flow than anything instantaneous.
Rinnai and Bosch continuous flow appear throughout, on mains gas and on LPG alike. They are excellent units and the caveat is not about the brand: on a pressure pump, confirm the flow rate before committing, because that is what decides whether the unit performs as intended.
Dux turns up across storage and heat pump, Solahart on the open north-facing roofs rural blocks tend to have, and Stiebel Eltron on heat pump conversions. Elements, thermostats, anodes, tempering valves and pressure limiting valves for the mainstream brands ride on the van, so a repair is usually same day.
We service and replace these systems as an independent licensed plumber. We are not an agent for, or endorsed by, any manufacturer.
Town water or pump, gas or electric. On tank supply the first two questions are about the pump and the filters, not the heater.
Flow rate, inlet screens, limiting valve and relief valve. If one of those is the cause, replacing the unit fixes nothing.
Most faults are done on the first visit. Where replacement is better value we show both figures rather than steering you.
Temperature checked at the outlets, compliance certificate issued on gas work, old unit taken away.
Tell us what feeds the house as well as what heats the water. On tank supply those are two different questions and only one of them is usually the problem.
Call 1300 381 569Start with what feeds it. On tank supply, check the pressure pump is running and building pressure, because no water into the heater looks exactly like a dead heater from the bathroom. On an electric storage tank, check whether the circuit has tripped, and bear in mind that a controlled load tariff only heats overnight, so a circuit that dropped out yesterday will not show until the stored water runs out. On gas, check the supply is on and on bottles check they are not empty. Past that it is a licensed job, because the pressure and temperature relief valve is not something to experiment with.
On pump-fed supply that is very often the pump rather than the heater, and it is the single most misdiagnosed fault out here. An instantaneous gas unit will not fire until enough water is actually flowing through it, and it needs that flow maintained to keep firing. A pressure pump that has weakened with age, or one that is undersized for the run, can sit just under that threshold. The unit lights, then drops out as the flow sags, then relights. People replace a perfectly good water heater over this. Tell us it is pump-fed when you book and we will check the supply before condemning anything.
Yes, and nobody mentions it at installation. Rainwater carries fine sediment, leaf matter and grit that town water does not, and it collects in the inlet filters and screens on the way into the system. A blocked inlet filter restricts flow, which on a continuous flow unit produces exactly the lukewarm behaviour above, and on a storage tank simply slows recovery. It is a five-minute maintenance item that goes unattended for years. If you are on tank supply, that filter is the first thing worth looking at.
Because they are the most common reason a tank dies young. A storage water heater has a pressure and temperature relief valve, and the incoming supply should have a pressure limiting valve holding it down to what the tank is rated for. If that limiting valve has failed, the tank spends its life at a pressure it was never designed for, the relief valve dribbles constantly, and the cylinder fails years early. It is a small, cheap, wearing part and almost nobody looks at it.
Rusty hot water usually means the sacrificial anode inside the tank is spent and the cylinder itself has begun to go, which is the beginning of the end rather than a fault to repair. Hot water running out faster than it used to is normally sediment settling in the bottom of the tank, taking up volume and insulating the element from the water. On tank-fed supply that happens faster, because the water arriving carries more of it to begin with.
A storage tank is generally eight to twelve years, and it reaches the upper end when the pressure limiting valve has been doing its job and the anode has been changed somewhere along the way. Continuous flow gas frequently runs fifteen to twenty. Heat pumps are newer in volume so there is less long-run data and the manufacturer warranty is the practical guide. Anything failing well short of those numbers usually has a reason upstream of it.
A service call and diagnosis is $120 to $250. Common repairs, elements, thermostats, relief and limiting valves, generally land between $200 and $600. A replacement electric storage tank supplied and installed is around $1,200 to $2,200 depending on size, continuous flow gas $1,600 to $2,900, and a heat pump $3,000 to $5,000 before any rebate. On pump-fed supply we check the pump and the inlet filters as part of the diagnosis rather than as an extra.
Tell us town water or tank, what type the unit is, and roughly how old. If it runs lukewarm or cuts out rather than failing outright, say that too, it points somewhere specific.
Fixed price agreed before we start, and a straight answer on repair against replacement.
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