Instant vs Storage Water Heaters in Singapore

By Amanda
July 14, 2025

Finding the right heater: Where to begin?

If you are getting a new home soon or starting to learn about water heaters, you’ve come to the right place. Searching for the right heater can be overwhelming. There are so many options in Singapore!

I’ll show you an easy too-long-didn’t-read (TLDR) comparison between 2 instant heaters and 2 storage heaters. These are 4 most popular heaters in Singapore. Use this guide for HDBs and condos. For landed homes, go here.

Disclaimer: I work at AOS Bath, and we are water heater specialists. We have storage and instant heaters, but not gas water heaters. Gas water heaters are only sold by CityGas (government).

That said, my priority is to lay out unbiased facts to help you to make an informed decision. It is not wise to promote a particular heater only to have you realise it is not what you wanted in the first place!

There are no right or wrong answers.

Every water heater caters to different needs. Choose one based on what your family requires. The final decision is yours

TLDR Water Heater Comparison

Energy saving

Energy saving

Energy saving

Energy saving

That’s was easy! Tell me more.

By looking at the chart, most of you will have a good idea of what water heater you want. Let’s go through a few more facts before making the final decision:

We’ll go deeper into:
• Price: installation, maintenance
• Energy saving: what each runs on, carbon footprint
• Running cost: assumptions and calculations
• Water pressure: how heaters affect water pressure, rain showers
• Size: size, location, design

Price

Gas instant heater: Lowest end is a $180 low flow rate model for HDB. Expect to pay $1300 for a higher end gas water heater heater with a higher flow rate.

Electric instant heater: $150 is the most basic water heater option in Singapore. Note: If you have 2 baths, you need 2 instant heaters as these cannot be shared.

Electric storage heater: $250 is the basic version with only heating light indicator. Expect to fork out at least $700 for more advanced digital water heaters equipped with timers and speed heating.

Heat pump: This renewable energy water heater extracts heat from the air and converts it to hot water. As with all green technology, cost is high but you get your money back fast because it saves at least $600/year.

Maintenance

Water Heaters are the highest wattage appliances in your home. For your safety, maintain them every 3 years. This prevents gas leaks and wiring issues. Water heaters with poor maintenance fail fast and pose a risk.

Well maintained water heaters can last over 10 years.

Energy Saving

Energy saving

Carbon footprint

Energy saving

Carbon footprint

Energy saving

Carbon footprint

Energy saving

Carbon footprint

Water heaters account for about 20% of the total electricity consumption in a home.

Gas instant heater: Gas is a cleaner source of energy compared to electricity.

Electric instant heater: Electric consumption is low due to low flow rate.

Electric storage heater: Highest energy consumer of the 4 heaters.

Heat pump: Lowest energy consumer, renewable energy. Uses free air heat to heat water.

Carbon footprint

Gas has a lower carbon footprint compared to electricity. In Singapore, we get by burning gas at a power station. Gas powered heaters skip this stage and have a lower carbon footprint.

Heat pumps have an even lower carbon footprint as they use very little electricity to heat water. Find out how they save money here.

Running cost per person

Assume:

Electric storage heater: An NUS study estimates a Singaporean takes 20 min x 2 showers a day. For HDB and condos, we reduced this to around 10 min per shower to get $10/month.

Electric instant heater: heaters are also 3000 watts, but their water pressure is lower. From $10/month, we reduce -40% to get $6/month.

Gas instant heaters cost about the same to run as Electric Storage. They are greener because gas appliances skip the power station, but running cost is not lower. For low flow rate HDB gas heaters, reduce 20% to get $8/month. High flow rate condo models run at $10/month.

Heat pump water heaters need electricity to run a fan that draws in free air heat. Reduce 75% to get about $3/month.

Calculate:

We used this Energy Calculator.

Water Pressure

Instant heaters are pressure reducing.

They slow down water flow rate, giving it time to heat up.

If water goes in at 10 lit/min, it may go out at 4 lit/min.

Storage heaters are pressure maximising.

If cold water goes into the tank at 15 lit/min, the hot water output is still 15 lit/min.

Why is high water pressure so important today?

In the past, high-flow rain showers and body jets did not exist. Today, they are trending. Our standards are getting higher. To support rain showers, a heater should produce 10 lit/min.

HDB gas water heaters are around 8 lit/min. When paired with rain showers, water pressure is low.

Size

Size, location and design

Gas instant heater: Installed at service yard or aircon ledge for safety. Small, leaves enough space for clothes rack or washing machine.

Electric instant heater: Installed at shower area. Compact and won’t take up too much space. For BTOs with concealed piping, there will be an extra exposed pipe to the shower area.

Electric storage heater: Bigger than instant heaters as it comes with a tank. Can install in common bathroom (up to 50 lit) or above false ceiling.

Heat pump heater: Biggest tank in this range because it is a tank + compressor. For HDB, heat pumps are often shifted to the yard. In condos, they can fit above false ceilings.

Electric storage heater, BTO
Gas heater, condo
Heat pump, BTO yard

How fast will you get hot water?

The closer the heater is to your shower point, the faster you will get hot water.

This is different from the heating time of a water heater. For more on that, check out this article.

Conclusion: Instant or Storage?

It’s all about personal preference, there are no right or wrong answers. Pick a heater that suits your lifestyle!

Unsure? Take a heater quiz for some answers.

Heaters that weren’t covered:

Digital water heaters

Digital heaters fall under the category of ‘Electric storage water Heaters’. They are more advanced, and have speed heating, hot water multiplier technology and built in timers.

Tankless water heaters

Tankless heaters like BathBox are a hybrid, between storage and instant heaters They have a higher water pressure of 7lit/min and are water saving.

Solar water heaters

Solar heaters, like heat pumps are renewable energy heaters. They are a type of storage water heater. Instead of using heat from the air, they use heat from the sun.

They are only suitable for landed homes, and are a less popular choice because of their lower efficiency compared to heat pumps.

Booster pump instant water heaters

These are instant water heaters for homes with extremely low water flow rate, 3 lit/min.

These small booster pumps bump up the flow to about 4 lit/min. They are quite noisy.

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The only storage heater that is also an instant heater

A. O. Smith has taken the water heating game to a whole new level and invented the fastest heating storage water heater in Singapore.

The Mini water heater

The latest technology brought in from A. O. Smith, is the Mini. Shown above, the Mini is an eighth generation digital system designed to heat water instantaneously. Basic electric heaters are our first generation systems.

How different is Mini from an instant heater?

While instant water heaters in Singapore produce hot water at the lower flow rate of 3 lit/min, the Mini operates at the same high water pressure as an electric storage heater, 8 lit/min.

Instant-heat tank technology

The internal tank of the Mini is designed differently from that of a regular heater. Its in-built sensors detect pockets of newly heated water and the tank is designed to ‘push’ this hot water to the user quickly. Regular electric heaters in contrast, rely on the slow process of convection where hot water gradually ‘rises’ to the user.

What are the practical applications?

Families that travel often

You usually arrive home in desperate need of a shower but a full tank of cold water translates to a twenty minute anticipatory wait. If you have a large family and one heater shared between two bathrooms, expect to wait twice as long because the lucky first batch of users will have cleaned out the entire hot water tank.

With Mini’s instant capabilities and zero wait time, hot showers are available for whole family the minute you step in your front door and power up your heater.

Serviced apartments

Tired travelers slip in their keycards in the power slot and go straight for a shower or bath to find there is no hot water! Well of course, you only powered the entire apartment mere seconds ago.

Serviced apartments and hotels require heaters which can provide a five-star bath experience in the shortest amount of time. Otherwise, they run up huge energy expenses leaving water heaters running indefinitely in a vacant room. Here’s where Mini shines.

In conclusion..

Water heating technologies have progressed quite a bit in the recent year. They save your precious time, provide comfort for your family and give you more opportunities to do the things that are meaningful to you. Use these technologies to your advantage today.

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