Most HDB bathrooms come down to two choices: an instant heater or a storage heater. Search instant water heater Singapore and you get a wall of models and wattages, none of which tells you which category you should be shopping in first. Price is the last thing that should settle it. What settles it is space, how much hot water your household uses at the same time, and when in your renovation the electrician turns up.
If your flat has existing gas piping there is a third option. We put all three side by side in our gas, electric and instant water heater comparison. This guide is about the two categories most HDB bathrooms actually choose between.
The short answer
One bathroom, one shower point, one or two people at home: an instant heater. More than one hot outlet running at once, two bathrooms off one system, or a family that showers back to back in the morning: a storage heater. That covers most flats. Below is why, and when it flips.
Start with the space above your shower
An instant heater is a compact unit mounted on the wall at the shower point. It needs wall space and an electrical point. That is the whole list.
A storage heater needs somewhere to put a tank. In most HDB bathrooms that is the ceiling void above a false ceiling, or a bracket high on the shower wall. Tanks come in a spread of sizes, and our own storage heater range runs from 15L up to 50L. A bigger tank buys more back to back shower time and eats more ceiling space. That trade off is most of the sizing decision.
If the false ceiling is already designed and nobody left a service opening for the tank, the decision has been made for you.
Measure before you shop. Ceiling height, void depth if there is a false ceiling, and a photo of the shower wall.
Then count your simultaneous outlets
This is the part people get wrong. Not how many showers your household takes in a day. How many hot outlets could be running at the same moment.
An instant heater heats water in one pass, as it flows through. Push more water through it and the temperature at the outlet drops, because the same element has more water to warm. Fine for one shower. Run a shower and a basin off the same unit and you feel it.
A storage heater has already done the heating. The tank holds a reserve, so temperature and pressure stay steadier across more than one outlet. The tank does run out, though. Then you wait for it to reheat.
Instant units are usually installed to serve one point of use. One unit feeding a shower, a basin and a second bathroom is storage territory.
Your showerhead is part of this decision
A large rain shower head moves a lot of water. Pair one with an undersized instant heater and the water arrives lukewarm, then the heater takes the blame for a mismatch that was designed in months earlier.
This happens often enough that many of the instant heaters we stock are sold as a matched package, heater and shower head together. If a rain shower is not negotiable in your bathroom, choose it first and size the heater around it. Note the model of the rain shower set you are considering and bring it up when you pick the heater.
Where this sits in a HIP or BTO timeline
HIP works and a BTO handover both run to a schedule you do not set. The heater decision has to land before tiling and the false ceiling go in, because that is when the electrical point and the mounting position get fixed.
Deciding late is what turns a clean install into chasing out finished tiles. Category first, then the model, then let the electrician position the point.
Either type is a licensed installation. Not a weekend job.
Running costs, honestly
Both types turn electricity into hot water at broadly similar efficiency. The difference is where the waste goes.
A storage heater keeps a tank warm, so it gives up a little heat to the bathroom while it sits there waiting. An instant heater has nothing standing, so it wastes nothing between showers, but it draws considerably more power while it is running.
Which one costs you less depends on your habits, not the category. A household that switches the storage heater on shortly before the evening showers is not paying much for standby. A household that leaves the tank on around the clock is. Anyone quoting you a fixed saving without asking how you use hot water is guessing.
What tends to fail first
A tank holds standing water permanently. An instant unit never does. Storage heaters want occasional servicing, and when a tank eventually goes, it goes wet. That is why the mounting position and where the water would drain matter as much as the model on the box.
Instant units have fewer parts sitting in water, and they are mounted in plain sight, so you spot a fault early. A tank seeping into a ceiling void can go a month before anyone notices.
Instant and storage side by side
| Instant heater | Storage heater | |
|---|---|---|
| Space needed | Compact unit on the wall at the shower point | A tank in the ceiling void or on a wall bracket |
| Hot water supply | Keeps going while it runs, one outlet at a time | A tank’s worth, then it reheats |
| Wait before first use | None | Reheat time from cold |
| Two outlets at once | Temperature drops | Holds steadier |
| Power draw | High while running | Lower, spread over longer |
| Heat lost while idle | None | Some, while the tank sits warm |
| Best fit | One bathroom, one or two people | Back to back showers, or more than one outlet |
Check these before you buy
- Ceiling void depth and shower wall space. Get the tape measure out
- The worst morning: how many hot outlets could run at once
- Whether a rain shower head is in the plan
- Whether a dedicated electrical point already exists or has to be run
- Where the water would go if a tank ever leaked
- Who is installing it, and where that falls in the renovation sequence
Once those six are answered, the category picks itself and you are only choosing a model. Browse our instant heaters and storage heaters ranges to see what each looks like at real sizes.
Still not sure which one your flat takes
Bring your bathroom measurements and a photo of the shower wall, and we will size it with you. Visit our showroom.
Frequently asked questions
Is an instant water heater enough for a HDB family bathroom?
For one outlet at a time, yes. If two people shower back to back, or a shower and a basin run together, a storage heater holds temperature more consistently.
What size storage water heater do I need for a Singapore HDB bathroom?
There is no single right number. It depends on how many hot outlets run at once and how much ceiling or wall space the tank has to fit into. Our range runs from 15L up to 50L. Bring your bathroom measurements and we will size it against your household.
Can I fit a storage heater without a false ceiling?
Usually yes, on a wall bracket mounted high. Check the wall can carry a full tank, and think about where the water would go if it ever leaked.
When in my renovation should I decide on the water heater?
Before tiling and the false ceiling. That is when the electrical point and the mounting position get fixed. Change your mind after that and you are chasing out finished work.
Is instant or storage cheaper to run?
It depends on how you use hot water, not on the category. Storage loses a little heat while the tank sits warm. Instant loses nothing standing but draws more power while it runs.
