Hot Water Running Cost Calculator
Estimate what electric storage, heat pump, gas continuous flow and gas storage hot water could cost to run using your household size and your actual electricity and gas rates.
Running-cost estimates are comparative only. Actual bills vary with climate, inlet-water temperature, system losses, tariffs, operating schedules, booster use, solar PV and household behaviour.
Running Cost Calculator
Enter usage rates from your bill for the best comparison. Estimates exclude fixed daily supply charges, purchase price, installation, solar export opportunity cost and model-specific standing losses.
What Does Hot Water Cost to Run?
Water heating is one of the biggest household energy uses in Australia. The running cost depends on how much hot water you use, the energy price you pay and how efficiently the system turns that energy into hot water.
How the Running Cost Calculator Works
The calculator first estimates how much hot water the household uses each day. It then estimates the thermal energy needed to raise that water by the selected temperature difference and applies a system-efficiency assumption before multiplying by your electricity or gas usage rate.
People × light, average, high or very-high hot-water use.
Daily litres are converted into thermal energy using the selected temperature rise.
Electric, heat pump and gas systems use different amounts of purchased energy to deliver the same heat.
Your entered electricity and gas usage rates produce the annual comparison.
Electricity and gas prices vary by retailer, network, tariff and state. The default fields are editable examples only and are not presented as an Australian average.
Why the Same Hot Water Can Cost Very Different Amounts
Heat pumps move heat from ambient air rather than generating all of it directly. Conventional electric storage uses a resistance element. Gas systems burn fuel and lose some energy through combustion and exhaust, with storage systems also exposed to tank heat losses.
| System | Calculator assumption | What it means | Best comparison use |
|---|---|---|---|
| Electric storage | COP 0.95 | Almost all purchased electrical energy becomes heat, with a small allowance before model-specific storage losses. | Comparing conventional electric resistance heating. |
| Heat pump | COP 3.5 | About 3.5 units of heat are modelled for each unit of electricity purchased. | Comparing efficient electric water heating under typical operating conditions. |
| Instant gas | 85% conversion | Purchased gas energy is converted to useful hot-water heat with combustion losses. | Comparing continuous-flow gas without storage losses. |
| Gas storage | 75% conversion | A conservative lower efficiency reflects combustion plus the weaker efficiency of storage gas. | Broad comparison with older-style gas storage. |
Electric Storage
Simple and often cheaper to buy, but conventional resistance heating generally needs much more purchased electricity than a heat pump to deliver the same amount of hot water.
Shop Electric Hot Water →Heat Pump
Australian Government guidance describes heat pumps as highly efficient and notes that they can use around 30% of the energy of conventional electric hot water, depending on model and operating conditions.
Shop Heat Pumps →Instant Gas
Continuous-flow gas avoids keeping a tank hot all day. Running cost still depends heavily on gas price, flow rate, temperature rise and actual efficiency.
Shop Instant Gas →Gas Storage
Gas storage has both combustion losses and storage losses. Government efficiency guidance generally places it behind heat pumps for household energy efficiency.
Shop Gas Hot Water →Electricity and Gas Rates Can Change the Winner
Running cost is not determined by system efficiency alone. A household on a cheap controlled-load electricity tariff can get a very different result from a household paying a high general-usage tariff. The same applies to gas, where usage rates and daily supply charges vary.
Can Solar PV Reduce Hot Water Running Costs?
Yes. Electric storage and heat pumps can be scheduled to operate when rooftop solar is producing, which can reduce grid electricity purchased for water heating. The economic value depends on solar generation, hot-water timing, system controls and what that exported solar electricity would otherwise have earned.
Heat Pump + Solar
A heat pump already needs relatively little purchased electricity for each unit of hot-water heat. Running during strong daytime solar production can reduce grid imports further.
Electric Storage + Solar
A conventional electric cylinder can act like a thermal battery when heating is deliberately shifted into solar-producing hours, provided the electrical and tariff arrangement allows it.
If the alternative was exporting that electricity for a feed-in tariff, using it for hot water has an opportunity cost. Compare avoided grid purchases with the value of the lost export credit.
How to Reduce Hot Water Running Costs
Shorter showers and efficient showerheads reduce litres that need to be heated.
Controlled load or time-of-use scheduling can lower the energy price paid for electric hot water.
Run compatible electric systems during rooftop-solar generation where practical.
A correctly sized heat pump can materially reduce purchased electricity compared with resistance electric heating.
What This Calculator Does Not Include
This is a buying and comparison tool rather than a model-specific energy-rating calculator. It does not include exact tank standing losses, heat-pump booster-element operation, compressor performance at a specific outdoor temperature, pipe losses, gas pilot consumption, appliance-specific test results, retailer discounts or fixed supply charges.
For a final product comparison, check the exact model's published energy performance and your current retailer tariff. The calculator is most useful for understanding how household demand, energy price and system efficiency interact.
Hot Water Running Cost Questions
Quick answers to common questions about electric, heat-pump and gas hot-water operating costs.
How much does a hot water system cost to run?
Is a heat pump cheaper to run than electric hot water?
Is gas or electric hot water cheaper to run?
Does off-peak electricity make electric hot water cheaper?
Does solar make hot water free?
How much energy does hot water use in an Australian home?
Why is my real bill different from the calculator?
Running Cost Is Only One Part of the Buying Decision.
Once you understand likely energy cost, compare purchase price, tank size, recovery, warranty, dimensions, stock and delivery across the actual systems.
