Boiling Water Taps and Undersink Boilers: Are They Worth It?
Everyone wants one after they see one at a mate's place. Half of them would be just as happy with the kettle.
An undersink boiling water unit is a small insulated tank that sits in the kitchen cupboard, keeps a few litres of water at up to 95°C, and feeds a dedicated tap on the bench so you get near boiling water instantly, without a kettle. The Stiebel Eltron HOT 2.6 N holds 2.6 litres, plugs into a normal 10 amp power point and sells for $999 with its tap. It is worth it if your house goes through a lot of tea, coffee or pasta water. If you boil the kettle twice a day, it is a nice toy, not a necessity.
Want your exact size? Our instant hot water sizing calculator works out the kW or litres a minute you need in winter, checks single or 3-phase power, then shows the units that fit.
What an undersink boiling water unit actually does
An undersink boiling water unit stores a small amount of water at near boiling temperature and delivers it through its own tap the moment you turn it on. It is not your normal hot water. It does not run the dishwasher, the sink mixer or the shower. It replaces the kettle, and that is the whole job.
The tank is well insulated, so it holds temperature with very little power once it is up to heat. You turn the tap, 95°C water comes out at up to 2.5 litres a minute, and cold mains water refills the tank behind it. The element then brings the new water back up to temperature.
Not to be confused with a point of use instantaneous heater. Those heat ordinary hot water at the tap for washing up and hand washing, usually to 50 or 60°C. We cover those in point of use hot water for kitchens, ensuites and granny flats.
The Stiebel Eltron HOT 2.6 N in numbers
The Stiebel Eltron HOT 2.6 N is a 2.6 litre undersink boiling unit rated at 1.6 kW that plugs into a standard power point and supplies water at up to 95°C. Here are the figures from the Stiebel Eltron product data.
| Spec | HOT 2.6 N |
|---|---|
| Tank capacity | 2.6 litres |
| Maximum temperature | 95°C |
| Rated output | 1.6 kW |
| Rated current | 7.3 A, single phase 230V plug in |
| Maximum flow rate | 2.5 litres a minute |
| Standby use | 0.2 kWh per 24 hours at a 65°C setting |
| Outlet type | Open (vented) outlet, 0 kPa, own tap only |
| Size (H x W x D) | 450 x 200 x 145 mm |
| Weight | 4.9 kg including tap |
| Approvals | WaterMark, IEC 60335-2-15, IP24 |
| Made in | Germany |
| Price | $999 including mono tap |
Prices current as of October 2026.
It also has a programmable timer, so it can sit cold overnight and while the house is empty, and a childproof push and turn tap. Mono taps come in chrome, brushed, nickel, black and gold, with an optional 3 in 1 tap that also does your normal hot and cold.
How much boiling water you get
A 2.6 litre undersink boiling unit gives you roughly eight to ten mugs in a row before the water starts to cool, which covers a family morning or a small office tea round. In practice you get a bit less than the full 2.6 litres at full temperature, because cold mains water mixes in as you draw it off.
Recovery is the limit, not the tank. By our maths, bringing a full 2.6 litres from 15°C to 95°C takes about 0.24 kWh. At 1.6 kW that is roughly 9 minutes for a completely drained tank, quicker for a couple of cups. A household never notices. A 20 person office at 10.30am might.
For anything bigger than a busy household or a small office kitchenette, a 2.6 litre unit is the wrong tool. Commercial boiling water units with bigger tanks exist for that. We do not stock them, and we would rather tell you that than sell you something that runs out every morning tea.
What it costs to run
An undersink boiling water unit costs around $24 a year in standby power at a 65°C setting, plus the energy to heat the water you actually use. Stiebel Eltron rates the HOT 2.6 N at 0.2 kWh a day of standby at 65°C. At 33 cents per kWh that is about 7 cents a day.
Set it to 95°C and standby goes up, because the hotter the tank, the faster it loses heat. Plan on more than the rated figure if you leave it at full boil all day. The timer is how you claw that back: switch it off overnight and on the days nobody is home.
The water you drink costs the same to heat either way. A litre from 15°C to 95°C is about 0.09 kWh, so 3 cents, whether it goes through a kettle or the boiling tap. Where the boiling tap wins is people who fill a 1.7 litre kettle to make one cup. Where the kettle wins is a house that makes one cup a day. For the wider running cost picture on electric units, see what an electric instant hot water system costs to run.
| Daily use | Boiling unit, approx per year | Verdict |
|---|---|---|
| 2 cups a day | About $30 | Kettle is cheaper. Buy it for convenience only. |
| 8 to 10 cups a day | About $45 to $50 | Roughly even with an overfilled kettle. Convenience wins. |
| Office, 30+ cups a day | About $105 | Worth it. Nobody stands around waiting on a kettle. |
Worked estimates at 33 cents per kWh, 250 ml cups heated from 15°C, standby at the rated 65°C figure. Prices current as of October 2026.
Who should buy one
An undersink boiling water unit is worth buying if your kitchen boils water many times a day or you want the kettle off the bench for good. The people who love them:
- Serious tea and coffee households. Four adults, plunger coffee, a pot of tea at 3pm. The tap pays for itself in time, if not in power.
- Small offices and break rooms. One tap, no kettle fights, no kettle left on the bench with the cord hanging off it.
- Renovators clearing the bench. If the new kitchen has a stone bench and no appliances on it, the boiling tap is how you get there.
- Cooks. Pasta water, blanching, stock. Starting from 95°C instead of 15°C saves real time on the stove.
Who should not bother
Skip the undersink boiling unit if you make one or two cups a day, you rent, or the cupboard under the sink is already full of a filter, a waste disposal and the bin. A $60 kettle does the same job for a light user. And if there is no power point under the sink, add the cost of an electrician to the sums before you decide.
Safety: 95°C water at the bench
Water at 95°C scalds on contact, so a boiling water tap needs a childproof control and a bit of household discipline. The HOT 2.6 N tap is push and turn: a small child pulling the handle gets nothing. That is the minimum you should accept on any boiling tap.
Practical rules we give every family: put the tap where kids are not reaching across it, do not put it next to the main mixer where someone can grab the wrong one, and set the temperature lower than 95°C if nobody in the house needs full boil. Tea is fine at 85°C. Most people never notice.
This is a separate rule from the 50°C limit on bathroom hot water. A dedicated kitchen boiling tap is a different product with its own requirements, and your plumber will install it to suit. The background on temperature limits is in why 50 or 60 degrees.
Installation
An undersink boiling water unit needs a cold water connection from a licensed plumber and a standard 10 amp power point under the sink. No dedicated circuit, no switchboard upgrade. The HOT 2.6 N draws 7.3 amps, less than a kettle.
Three things that catch people out:
- It is an open outlet unit. The tank is vented through its own tap. You cannot hook it up to your existing mixer or any other tap. It comes with its own, and that is the one you use.
- It drips while it heats. Water expands as it heats and a vented unit lets that out through the spout. A few drips during heat up is normal, not a fault.
- You need a tap hole. Either a spare hole in the sink or a new one drilled in the bench. Stone benches need a stonemason with a core drill, not a cordless and optimism.
Hard water is the other one. In areas with high calcium, the tank scales up over time like a kettle does. Descale it when flow drops or it starts to sound noisy. Rainwater and soft mains towns barely notice.
Pairing it with point of use hot water
A boiling water unit and a point of use instantaneous heater do two different jobs and plenty of kitchens run both. The boiling unit handles tea and cooking. A DHCE 8/60 under the same sink handles washing up at 60°C, with no wait for hot water from a system at the far end of the house. For a basin or a smaller job, the DHCE 6/50 is enough.
Worth knowing: the DHCE units need their own 30 or 40 amp circuit, unlike the boiling unit. Two units, one cupboard, one electrician visit if you do them together.
Frequently asked questions
Are boiling water taps worth it in Australia?
Boiling water taps are worth it in Australia for households and offices that boil water many times a day, because they deliver 95°C water instantly and cost roughly $24 a year in standby power for a unit like the Stiebel Eltron HOT 2.6 N. For someone who makes one or two cups a day, a kettle is cheaper and does the same job.
How much does an undersink boiling water unit cost to run?
An undersink boiling water unit like the Stiebel Eltron HOT 2.6 N uses about 0.2 kWh a day in standby at a 65°C setting, which is around $24 a year at 33 cents per kWh. Heating the water you use adds about 3 cents per litre, and a higher 95°C setting increases standby loss.
Do boiling water taps need a dedicated circuit?
Small undersink boiling water units do not need a dedicated circuit. The Stiebel Eltron HOT 2.6 N draws 7.3 amps and plugs into a standard 10 amp power point under the sink, though a licensed plumber must connect the water and an electrician may be needed if there is no power point in the cupboard.
How hot is the water from a boiling water tap?
Water from an undersink boiling water tap like the Stiebel Eltron HOT 2.6 N comes out at up to 95°C, which is near boiling and hot enough for tea, coffee and cooking. The temperature can be set lower, and many households run it at 85 to 90°C to reduce scald risk and standby power.
Can I connect a boiling water unit to my existing kitchen tap?
You cannot connect an open outlet boiling water unit like the Stiebel Eltron HOT 2.6 N to your existing kitchen mixer, because the tank vents through its own dedicated tap. The unit comes with its own mono tap or an optional 3 in 1 tap, which needs a spare tap hole in the sink or bench.
Want one, or not sure it is worth it?
Tell us how many people use the kitchen and how often the kettle goes on, and we will tell you straight whether a boiling unit earns its spot under your sink. If what you really want is faster ordinary hot water at the tap, that is a different product, and we will point you at it.
Ask us whether a boiling water unit suits your kitchen →
Shop undersink water heaters →
Or browse the Stiebel Eltron range, every instant hot water system we stock, and the full water heating collection.
This guide is general information for Australian households and is not a substitute for advice on your specific home and site. Running costs and recovery times are worked estimates based on typical mains water temperatures and an assumed electricity price. Boiling water units must have their water connection installed by a licensed plumber, and any new power point or circuit must be installed by a licensed electrician. Electric instantaneous water heaters need a dedicated circuit sized to the unit. 3-phase units need a 3-phase power supply. Gas continuous flow units must be installed by a licensed gas fitter. Water at 95°C causes severe scalds; supervise children and use the childproof tap control. Confirm final selection with us or your installer before you buy.