What Water Heater Tank Size to Get?

By Amanda
February 2, 2026

Water Heater Tank Size Guide for Singapore

The #1 Biggest Mistake is getting a tiny storage tank just to blend into your interior design. If you do this, you may:
• Waste lots of time waiting for your hot water
• Run out of hot water in the middle of your shower!! Brrrr!!

The smart thing to do is: choose a water heater based on your family's needs. This guide will show you how!

Size Guide for HDB / Condo

The Most Popular is Gen 6, 40 lit. Why?
• Speed heating functions
• Gives you double the hot water of Gen 1
• More features here: Digital Heat Technology.

The Most Green are Heat pumps:
• Run on renewable energy.
• Use free heat energy in the air to heat water. • Heat pumps are good for large families or bathtub use.

How Much Hot Water Do You Need?

Everyone's shower time is different!

This is how many minutes of hot water they needs:

Hot water time:
• when we turn on the tap and the hot water flows
• is shorter than total shower time
• does not count time to change, soap, or dry off

How Much Hot Water Can a Heater Produce?

• Every storage heater can produce a fixed amount of hot water.
• The bigger the size, the more the hot water.
• Hot water is heated while you shower, but not fast enough to be infinite.

This table shows how much hot water you get from each heater:

Top Choice:

• For HDB: 40 lit, Gen 6 Digital
• For Condo: 50 lit, Gen 6 Digital for tubs

Size Guide for Landed Homes

There are two layouts for landed homes. Individual and Central Heating.

Most new landed homes use a central heater
• Easier to maintain
• Lower power loading

Individual Heating
• one heater supplies to one bathroom
• heater installed in false ceiling
• use the size guide above for HDB/Condo

Central Heating
• one heater for the whole house
• installed at air con ledge or roof
• use this guide below or send us your floor plan

Heat Pumps
• Costs more than normal electric heaters
• Good water pressure
• Running cost: saves 80% vs. Electric

For central heaters, heat pumps are the #1 popular choice because of 80% energy saving rate.

Size Guide for Bathtubs

Bathtubs need more hot water. Why?
• need to fill in lots of water at one go
• water fills at high flow rate
• plus one more shower at the end

Still Not Sure?

We're the Experts. Let us help you!
• take this quiz so we can understand your needs
• let us know what heater you have in mind, we'll let you know if it is suitable

It has served our family well so far, we are using the Gen 8 model. Hot water is quite instant when we turn it on.

Overall a good buy, good customer service by the sales person at their showroom too, very patient on the walk through with their range of products and not pushy on selling.

Terence Leong

Google review

Very good service from Sanny, Mr. Lim, Moez, Pankaj and Abdullah. Installation was neat and spot on. Great practical advice from Sanny and Mr. Lim on how to maximize cost savings, they were never pushy or promoted the most expensive product but the one that suited my family.

Darren Leong

Google review

I got my water heater directly from AOS distributor. Sales lady explained their products in very clear and concise manner, and I did not have any difficulty choosing the right size and model for my new home.

Doreen Teo

Google review

They answered all my queries promptly. I also visited their showroom to look at the heaters and ask questions to clear my doubts. Thereafter I made a decision to invest in the heater. No regrets whatsoever. One of the best investments I have made.

Swaminathan Panchapagesan

Google review

Heater Size Guide FAQ

What happens when I run out of hot water?

On a storage heater, you’ll find yourself adjusting the mixer to the hot side more and more.

Hot water cut off is not sudden, it is gradual!

Size your heater right and you won’t run out of hot water often.

What to do if the heater size I want can't fit?

Get a digital heater (Gen 6) to max out your hot water regeneration rate.

Compared to Gen 1 heaters, Gen 6 heaters can produce 2 times the amount of hot water for the same tank size.

You can also stagger your shower time. Give enough time in between showers so the heater has time to fully ‘charge’ before the next person goes in.

If the space is very small, you can consider a tankless model like the BathBox.

Learnt something new? Share it!

Avoid These 6 Warranty Pitfalls at All Costs

Beware of a Too-Good-to-be-True, Ultra Long Warranty!

Don’t be me. I learnt this the hard way buying my Samsonite luggage. Buying a "lifetime" warranty seemed like the best deal. Until I brought it in to change a part that fell out.

Then they pulled out this crazy list of terms and conditions that made me give up.

For appliances like water heaters, the concept is the same. Not all warranties are equal. Understand this before you buy. Know what to look out for. This will save you precious time and emotional frustration.

1. Keep Your Eyes Peeled for a 'Full Warranty'. This is the Best Type of Warranty and Very Rare. Go for FULL Coverage Whenever Possible.

Full warranties are scarce and hard to find.

Good news is... 'hard to find' does not mean it is impossible to find.

You want this Full Warranty because it protects you more than it protects the company. That is the idea right?

You want to be fully covered to be exempt from paying for hidden costs. This needs to cover everything from labour, parts cost and transport. A full onsite warranty.

The only thing that is not covered are installation faults. But it is fair to exclude this from coverage. If your installer damaged the product because of his lack of skill.. then you go after the installer.

2. Don't Just Get Full Coverage... Get the LONGEST Possible Full Coverage.

When buying stuff at Harvey Norman, they always ask if you want to upgrade your warranty and add 2 to 5 years to it.

While it's always tempting to think, Nahhhh. I've already spent $5k on this fridge!! Why would I want to top up YET another $800 bucks for incidents I cannot forsee??

WELL. Life is about planning for incidents you cannot forsee. And from personal experience, Extended warranties have saved my wallet more than half the time. So grateful for buying the extension for the last few big-cap electronic purchases. I put my faith there!

In Singapore, the average lifespan of a heater is 5 years. This means many heater companies will give you a 1 Year Full warranty.

Better brands last longer, so they go up to 3 Years Full warranty.

If your home situation is long-term, aim for 3 years. You save more in the long run going for quality and the longest possible warranty coverage.

If I don't Have a 'Full Warranty'... What am I Getting?

If what you have on your hands isn't a full warranty... You may have a partial warranty.

In that case, you have to be extra careful.

Partial warranties cover only certain parts

3. Now Hang On Tight, Don’t Fall off Your Chair... We’re Coming to the Most Well Kept Secret About Partial Warranties..

Of course a partial warranty sounds appealing!! Who doesn't like the sound of a 10-year warranty? But they are misleading and even a tad dishonest.

Let me let you in on a secret. A 10-year warranty on a heating element might seem like a great deal.. but the industry secret is that the heating element rarely fails. It’s the other parts like wires and thermostats that will need repair sooner. If these aren’t covered, you could end up paying out of pocket for repairs.

Usually, companies who play this game are not interested in servicing you. They are excited to find out if you’ve exceeded your 1-year warranty. Then they can slap on some charges for back end sales. It's a horrible way to do business.

Be wary of those partial warranties!!

Heating elements are hardly ever replaced.. in all my years of being in the heater industry, I’ve only seen elements break down less than 5 times!!

4. Trust me on This, for Heaters.. Always Buy Local. Forget That Awesome Deal You Saw on Taobao.

Absolutely NO taobao for water heaters!! It will be the worst decision ever.

You need a local warranty. If there's a problem.. there is no way you can fix it yourself. You are not superman!!! Even if you ARE Superman, you have no Time!!

When you buy local, you're actually buying access to a valuable local support network.

I've heard horror stories of unapproved heaters bought online that fail at the worst times. Imagine: Chinese New Year no hot water?!! Your wife and kids are giving you pressure? Now good luck getting support over taobao chat.

Actually, at that point you’ll need more than luck to survive.

Don't ruin things for yourself. Always buy local when it comes heaters. Thank me later.

Heaters are one of the hardest appliances to troubleshoot.

5. Hidden Costs Here, Hidden Costs There, Hidden Costs EVERYWHERE!

If normal transport charges are $100+... Why are you getting charged $250????

I've heard this happen to people who are still locked in under their 'warranty period'. They can't go to a 3rd party to repair or their warranty may be void. It's a minor wire repair but they have to cough up hundreds $$$$$.

They are stuck in what we call a ‘bo-pian’ or no-choice situation.

It is downright dreadful, but sad to say.. This kind of back-end sales tactic has happened before and will happen again.

Out of frustration, some even decide to change their whole heater to another brand. It’s a good move because you avoid dealing with dishonesty.

On the other hand, it’s very expensive…

You can avoid this heartache by doing some homework. Buy from a reputable company.

6. Whenever Possible, Buy Direct from the Main Distributor

When I bought my first Dyson.. I went to a Reputable department store along Orchard Road. They were running a promo I couldn't resist.

Things went fine as long until my Dyson stopped working.. then the nightmares began. I got thrown around department after department of red tape.

Need to check invoice.
Need to look up sales person.
Oh.. Must send to HQ for inspection.
Now we need to order special parts.

It was a simple problem but so many layers of people and paperwork. Drove me nuts.

From that I learnt my lesson, always buy direct.

Now I get my Dyson from the main distributor. Their turnover is fast. I have absolute confidence I'm getting the latest version free from bugs and defects.

If they have issues with a model, they are upfront and transparent with me. Because I am their direct customer, they will take care of me first.

Response is also much faster!!

Sometimes, they also waive charges. Now, I'm not saying to go in with the expectation of free service. Everyone has to earn a fair wage. But I can feel the difference in the quality of customer service.

Same idea with water heaters. Want faster service? Buy direct.

7. Are You Serviced By a Bot or a Human Being?

Of course you can tell. Everything is different when it's a real person on the other end of the line.

Service is faster.

Arrangements are flexible.

You get accurate answers.

Because a real person understands your needs. A bot doesn't.

Conclusion

Singaporeans and hot water have a special relationship. We take it for granted when it is there, but we go crazy when deprived of it!!

Understanding your water heater warranty can make or break your hot water experience.

Hope the tips I’ve shared here on warranties will help you in some way!

What Water Heater Tank Size to Get?

Water Heater Tank Size Guide for Singapore