Electric Hot Water Systems: Storage vs Instant Electric, Sizes, Costs and What to Choose

Electric hot water systems are one of the most common choices for Australian homes because they are simple, familiar and suitable for properties without gas. They can be a practical replacement when an old electric storage tank fails, but choosing the right system is not just about picking the cheapest unit.

The best electric hot water system depends on household size, daily hot water use, tank capacity, electrical setup, tariff, installation location, access, running cost goals and whether a standard electric storage system or a heat pump would make more sense.

For customers comparing products online, Installed Today’s Electric Hot Water Systems range is the best starting point. You can compare standard electric storage systems, Instant Electric Hot Water Systems, 250L Electric Hot Water Systems, 315L Electric Hot Water Systems, 400L Electric Hot Water Systems and energy-efficient alternatives such as Heat Pump Hot Water Systems.

Quick Answer

Best for simple replacement: electric storage hot water systems

Best for compact spaces or point-of-use use: instant electric hot water systems

Best for small to medium families: 250L electric storage systems where the household demand suits

Best for larger homes: 315L or 400L electric storage systems, depending on usage and tariff setup

Best premium electric option: Rheem Stellar stainless steel electric systems

Best value-focused options: Vulcan, Rinnai and Dux electric storage systems

Best alternative for lower running cost potential: heat pump hot water systems

Main thing to avoid: choosing the same size again if the old system was already running out of hot water

What Is an Electric Hot Water System?

An electric hot water system uses electricity to heat water for showers, taps, kitchens, bathrooms and laundries.

There are two main types:

electric storage hot water systems
instant electric hot water systems

Electric storage systems heat water inside a tank and store it until the household needs it.

Instant electric systems heat water as it flows through the unit, without storing hot water in a tank.

Most homes replacing an older electric hot water system are usually comparing storage tanks. Instant electric systems are more commonly suited to smaller spaces, point-of-use applications or specific locations where a tank is not practical.

Electric Storage Hot Water Systems

Electric storage hot water systems are the most common electric option. They heat water using an electric element and store that hot water inside an insulated tank.

They are popular because they are:

simple to understand
quiet in operation
widely available
suitable for homes without gas
available in many sizes
usually cheaper upfront than heat pumps
practical for like-for-like replacements

Installed Today’s Electric Hot Water Systems collection includes electric storage systems from brands such as Rheem, Rinnai, Dux, Vulcan and Aquamax.

The main limitation is running cost. A standard electric storage system will usually have higher running cost potential than a well-matched heat pump hot water system, especially where the home has rooftop solar and a suitable outdoor location for a heat pump.

Instant Electric Hot Water Systems

Instant electric hot water systems heat water on demand. They do not store hot water in a tank.

They can suit:

small spaces
units
sinks
bathrooms
kitchenettes
point-of-use applications
low to moderate demand areas
locations where a storage tank is not practical

Installed Today’s Instant Electric Hot Water Systems category is the best place to compare compact electric options.

However, instant electric systems are not automatically suitable for every whole-home application. They can require significant electrical capacity, and flow rate depends on the unit, incoming water temperature and required temperature rise.

Before ordering instant electric supply only, your licensed installer or electrician should confirm that the electrical supply, circuit, switchboard and installation location are suitable.

Electric Storage vs Instant Electric

Electric storage and instant electric systems suit different needs.

For most family homes, electric storage is usually the more common replacement. For smaller applications, instant electric may be the better fit.

What Size Electric Hot Water System Do You Need?

Sizing is one of the most important parts of choosing an electric hot water system.

A system that is too small may run out of hot water. A system that is too large may cost more upfront and store more hot water than the household needs.

Common electric storage sizes include:

50L: small point-of-use or low-demand applications
125L: small households, units or granny flats
160L: small homes or moderate-use households
250L: small to medium families
315L: larger households or higher daily demand
400L: large households, off-peak setups or heavy usage

The right size depends on:

number of people in the home
number of bathrooms
shower length
bath use
laundry habits
kitchen hot water use
morning and evening peak demand
whether multiple showers run close together
whether the home uses off-peak electricity
whether the old system supplied enough hot water

If the old system constantly ran out of hot water, do not automatically replace it with the same size.

250L Electric Hot Water Systems

A 250L electric hot water system is one of the most common family-sized electric storage options.

It may suit:

small to medium families
townhouses
rental properties
homes with one or two bathrooms
moderate daily shower use
households replacing an existing 250L system that worked well

Installed Today’s 250L Electric Hot Water Systems category includes common options such as Rheem, Rheem Stellar, Rinnai, Dux, Vulcan and Aquamax.

Popular options to compare include:

Rheem 250L Electric Hot Water System
Rheem Stellar 250L Electric Hot Water System
Vulcan 250L Electric Hot Water System
Vulcan DuoMax 250L Electric Hot Water System

A 250L tank may not suit larger families, homes with long showers, heavy bath use or multiple bathrooms running close together.

315L Electric Hot Water Systems

A 315L electric hot water system gives more stored water than a 250L tank and can suit homes with higher daily demand.

It may suit:

larger families
homes with more frequent shower use
households replacing an existing 315L system
properties with off-peak electric hot water
homes where a 250L tank was not enough
higher morning or evening peak demand

Installed Today’s 315L Electric Hot Water Systems category is a useful starting point if you need more stored water than a 250L system.

A 315L system can be a good middle ground between standard family storage and a large 400L tank.

400L Electric Hot Water Systems

A 400L electric hot water system is a large storage option for homes with high hot water demand.

It may suit:

large families
homes with multiple bathrooms
heavy bath use
long back-to-back showers
properties using off-peak electricity
households replacing an existing 400L tank
homes where 250L or 315L would not be enough

Installed Today’s 400L Electric Hot Water Systems category is best suited to customers who know they need a larger storage tank.

A 400L system should be chosen carefully. It can be useful for high-demand households, but it may be oversized for smaller homes and can cost more upfront.

Electric Hot Water Brands to Compare

Common electric hot water brands include:

Rheem
Rheem Stellar
Rinnai
Dux
Vulcan
Aquamax

Each brand has different strengths. The right choice depends on the home, budget, tank size, warranty preference, water quality, maintenance expectations and installation requirements.

Rheem Electric Hot Water Systems

Rheem is one of Australia’s best-known hot water brands and is commonly compared for standard electric storage systems.

A Rheem electric system may suit customers who:

prefer a well-known brand
are replacing an older Rheem unit
want a standard electric storage tank
want broad product support
are comparing 250L, 315L or 400L electric systems

The Rheem Hot Water Systems collection is useful for comparing Rheem electric, gas, heat pump and other hot water options.

The Rheem 250L Electric Hot Water System is a common family-sized electric storage option for homes with typical 250L demand.

Rheem Stellar Electric Hot Water Systems

Rheem Stellar electric systems are premium stainless steel electric storage systems.

The key difference is that Rheem Stellar electric models use stainless steel cylinder construction and do not require a sacrificial anode. This can reduce maintenance compared with many standard steel tank electric systems.

The Rheem Stellar 250L Electric Hot Water System may suit customers who:

want a premium electric storage system
prefer stainless steel construction
want reduced anode maintenance
are planning long-term ownership
are comfortable paying more upfront
have water quality suitable for stainless steel

Rheem Stellar is usually the stronger premium choice, while standard Rheem, Vulcan, Rinnai and Dux electric tanks may suit customers focused on upfront value.

Vulcan Electric Hot Water Systems

Vulcan electric hot water systems are practical, value-focused electric storage units.

They may suit:

budget-conscious homeowners
rental properties
simple like-for-like replacements
households that do not need premium features
customers comparing value over brand prestige
homes replacing standard electric storage tanks

Installed Today’s Vulcan Hot Water Systems collection includes Vulcan electric storage, DuoMax electric and gas storage options.

The Vulcan 250L Electric Hot Water System is a practical family-sized option where the household demand suits a 250L tank.

Rinnai Electric Hot Water Systems

Rinnai electric hot water systems are often compared as value-focused alternatives to Rheem and Dux.

Rinnai may suit customers who:

know the Rinnai brand
want a practical electric storage replacement
are comparing price and availability
need a standard 125L, 160L, 250L or 315L style system
want to compare electric with Rinnai gas or heat pump options

The Rinnai Hot Water Systems collection is useful for customers comparing Rinnai electric, gas and heat pump systems.

Dux Electric Hot Water Systems

Dux is a well-known Australian hot water brand with practical electric storage systems for different household sizes.

Dux may suit customers who:

want an Australian hot water brand
are replacing a standard electric tank
need a 125L, 250L, 315L or 400L style system
want a practical steel tank option
are comparing alternatives to Rheem, Rinnai and Vulcan

The Dux Hot Water Systems collection is worth reviewing if you want to compare Dux electric and gas options.

Electric Storage vs Heat Pump Hot Water

Before choosing a standard electric storage system, compare heat pump hot water.

A heat pump uses electricity to draw heat from the surrounding air and transfer that heat into stored water. It usually costs more upfront than standard electric storage but can reduce electricity use over time when installed and set up correctly.

Standard electric storage may be better when:

you want the lowest upfront cost
the old electric system worked well
you want a simple replacement
you need quiet operation
the site does not suit a heat pump
you already have a licensed installer arranged

Heat pump hot water may be better when:

you want lower running cost potential
the home has rooftop solar
there is suitable outdoor space
airflow and drainage are available
noise placement can be managed
you are replacing an older electric storage tank
you want a more efficient electric upgrade

Installed Today’s Heat Pump Hot Water Systems category is the best place to compare heat pump alternatives. For common household sizes, review Medium Heat Pump Hot Water Systems 200L–280L and Large Heat Pump Hot Water Systems.

Electric Hot Water and Rooftop Solar

Electric storage hot water can sometimes be timed to run during solar production hours, depending on the setup, electrical controls and tariff arrangement.

However, heat pump hot water is often a stronger match for homes with rooftop solar because a heat pump can use less electricity than a standard electric element while heating during the day.

If your home has rooftop solar, compare:

standard electric storage with timer control
heat pump hot water with daytime operation
tariff setup
household hot water demand
tank size
installation location

A licensed electrician or installer should confirm whether the home’s electrical setup can support the preferred arrangement.

Off-Peak Electric Hot Water

Off-peak electric hot water can reduce running costs where the home has the right tariff and wiring. The system heats water during lower-cost periods and stores it for later use.

Off-peak setups often need larger tanks because the system may only reheat during set times.

Off-peak electric may suit:

larger storage tanks
homes with predictable hot water use
households that need stored water across the day
properties already wired for off-peak hot water

Before choosing off-peak electric storage, check:

whether the home has off-peak wiring
whether the tariff still offers a real saving
whether the tank is large enough
whether the household runs out before reheating
whether a heat pump would be better long term

Off-peak can help, but it does not automatically make standard electric storage the lowest running cost option.

Electric Hot Water Running Costs

Electric hot water running costs depend on the system, tank size, tariff and household use.

Running costs are affected by:

daily hot water use
number of people in the home
shower length
tank size
element rating
electricity tariff
off-peak or continuous power setup
rooftop solar availability
timer settings
pipe insulation
valve condition
maintenance condition

A standard electric storage system can be cheap to buy but more expensive to run than a well-matched heat pump.

This is why the best choice is not always the cheapest unit. The better decision is the system that balances upfront cost, running cost, installation requirements and household demand.

Electric Hot Water Installation Requirements

Electric hot water installation should be handled by licensed professionals.

A proper installation may need to consider:

electrical supply
circuit suitability
switchboard capacity
element rating
valves
tempering valve requirements
pressure limiting valve requirements
drainage
overflow discharge
access
safe delivery and positioning
old unit removal
pipework changes
current compliance requirements

A like-for-like replacement can still need extra work if the old installation does not meet current standards or if the new unit has different dimensions or connection positions.

Supply Only vs Supplied and Installed

Installed Today offers supply-only ordering for customers who already have their own licensed installer arranged. Supply-only pricing is for the product only and does not include installation, valves, electrical work, pipework changes, drainage work, old unit removal, disposal or compliance upgrades unless those options are clearly selected or shown on the product page.

Supplied-and-installed options may be available on selected products in eligible Brisbane and Gold Coast service areas. Availability depends on the product, address, access, existing setup, electrical suitability, drainage, required extras and site requirements.

Before ordering supply only, make sure your licensed installer confirms the selected electric hot water system suits your home, household demand, electrical setup, installation location, access path, drainage, valves and compliance requirements.

Brisbane and Gold Coast Buying Context

For Brisbane and Gold Coast homes, electric hot water systems are commonly chosen for straightforward replacements where the existing electric tank has failed and the customer wants a familiar system.

Local homes should check:

whether the current system is 125L, 160L, 250L, 315L or 400L
whether the old system supplied enough hot water
whether the new tank fits the same space
whether drainage is suitable
whether valves need replacing
whether electrical work is required
whether the home uses off-peak or continuous tariff power
whether rooftop solar is available
whether heat pump hot water should be compared
whether supply only or supplied and installed is preferred
whether access allows safe delivery and positioning

South East Queensland’s warmer climate can also suit heat pump hot water, so customers replacing electric storage should compare heat pumps before automatically buying another standard electric tank.

Common Electric Hot Water Problems

Common electric hot water problems include:

not enough hot water
slow recovery after heavy use
no hot water
tripped circuit breaker
faulty element
faulty thermostat
water leaking from valves
excessive relief valve discharge
rust or corrosion around fittings
anode wear on steel tanks
poor water pressure from old valves or plumbing
incorrect system size for the household

A licensed plumber should inspect leaks, valves, pressure issues and installation faults. A licensed electrician is required for electrical testing, element replacement, thermostat work and circuit issues.

Homeowners should not attempt electrical hot water repairs themselves.

Electric Hot Water Maintenance

Electric storage systems are simple, but they are not maintenance-free.

Maintenance considerations include:

checking for valve leaks
watching for excessive overflow discharge
keeping the system accessible
checking for rust or corrosion signs
following anode maintenance requirements on steel tanks
checking the owner’s guide for service intervals
having electrical issues checked by a licensed electrician
booking licensed servicing when needed

The sacrificial anode is especially important in steel tank systems because it helps protect the cylinder from corrosion. Rheem Stellar stainless steel electric systems are different because they do not require a sacrificial anode.

Before Ordering Checklist

Before ordering an electric hot water system, check:

current tank size
household size
number of bathrooms
daily shower habits
whether the old system supplied enough hot water
whether a larger or smaller tank is needed
whether the home uses off-peak power
whether rooftop solar is available
whether heat pump hot water should be compared
whether the product dimensions suit the space
whether access is suitable for delivery
whether drainage is compliant
whether valves need replacing
whether electrical work may be required
whether supply only or supplied and installed is required
whether your licensed installer has confirmed suitability

This helps avoid ordering a system that is too small, too large, too expensive to run or unsuitable for the site.

Which Electric Hot Water System Should You Choose?

Choose standard electric storage if you want a simple, quiet and familiar replacement.

Choose instant electric if you need compact point-of-use hot water and the electrical setup is suitable.

Choose a 250L electric system if you have a small to medium household and the previous 250L tank worked well.

Choose a 315L electric system if your household needs more stored hot water than 250L.

Choose a 400L electric system if your home has high demand or off-peak storage needs.

Choose Rheem Stellar if you want a premium stainless steel electric system with reduced anode maintenance.

Choose Vulcan, Rinnai or Dux if you want a practical value-focused electric storage replacement.

Choose a heat pump if your main goal is lower running cost potential and the home has suitable outdoor space, airflow and drainage.

Long-Tail FAQs

Are electric hot water systems good?

Yes, electric hot water systems can be a good choice for homes that want a simple, familiar and quiet hot water replacement. They are especially practical where gas is not available or where the existing electric setup already suits storage hot water.

Is electric hot water expensive to run?

Standard electric storage can be more expensive to run than heat pump hot water. Running costs depend on tank size, electricity tariff, household usage, off-peak setup, timer settings and maintenance.

Is a heat pump better than electric storage?

A heat pump may be better if the goal is lower running cost potential and the home has suitable outdoor space, airflow and drainage. Electric storage may be better for lower upfront cost, simple replacement and silent operation.

Is instant electric hot water good for a whole house?

Instant electric can suit some applications, but it is not automatically the best whole-home solution. Electrical supply, circuit capacity, flow rate and temperature rise must be checked by a licensed professional.

What size electric hot water system do I need for a family?

A 250L system may suit some small to medium families. A 315L or 400L system may be better for larger households, long showers, multiple bathrooms, bath use or off-peak setups. The right size depends on usage, not just the number of people.

Should I replace my old electric hot water system with the same size?

Only if the old system supplied enough hot water and suited the household. If it regularly ran out, compare a larger tank or heat pump before replacing like-for-like.

Can electric hot water work with rooftop solar?

Yes, some electric hot water systems can be set up to use more daytime solar power depending on timers, tariffs and electrical setup. Heat pump hot water is often worth comparing because it can use less electricity than standard electric storage.

Can I buy an electric hot water system supply only?

Yes. Supply only is suitable if you already have your own licensed installer arranged. The product price is for the unit only and does not include installation, valves, disposal, electrical work, pipework changes or compliance upgrades unless selected separately.

Can I order an electric hot water system supplied and installed?

Supplied-and-installed options may be available on selected products in eligible Brisbane and Gold Coast service areas. Availability depends on the product, address, access, existing setup, electrical suitability, valves, drainage and required extras.

What is the main mistake when buying electric hot water?

The main mistake is choosing on price alone without checking size, household demand, electrical setup, installation requirements and whether a heat pump would be better long term.

Final Word

Electric hot water systems remain a practical choice for many Australian homes. They are simple, familiar, quiet and available in a wide range of sizes. For like-for-like replacements, a standard electric storage tank can make sense where the old system worked well and the household wants a straightforward solution.

However, electric storage is not always the best long-term option. If running cost reduction matters, heat pump hot water should be compared before ordering another standard electric tank. If space is limited, instant electric may suit smaller applications. If premium low-maintenance electric storage is the goal, Rheem Stellar may be worth comparing.

Start with Installed Today’s Electric Hot Water Systems, compare 250L Electric Hot Water Systems, 315L Electric Hot Water Systems, 400L Electric Hot Water Systems, Instant Electric Hot Water Systems and Heat Pump Hot Water Systems before choosing the best fit for your home.