3L vs 5L Instant Geyser: Which Is Better for Your Kitchen or Small Bathroom?

A 3L instant geyser is the better pick for a kitchen sink or a wash basin, and a 5L one is the better pick when two people use the same tap back to back or when it also serves a small bathroom. Orient Electric 3L instant geysers are priced from Rs. 2,499 to Rs. 4,430, and the 5L range (5.5L and 5.9L tanks) from Rs. 3,349 to Rs. 4,800. Both sizes use a 3000W element, so a bigger tank does not heat faster. It gives you more hot water ready to use. This guide shows how much more, with worked numbers.

The 3L and 5L instant geysers at a glance

A larger tank does not always cost more. The Calidus Pro 5.5L at Rs. 3,349 is priced below the Primus 3L at Rs. 3,810. What you pay for in the 3L range is mostly warranty and pressure rating, not size. See the full 3 litre and 5 litre ranges for what is in stock today.

What the extra 2.5 litres gives you

An instant geyser holds a small tank of water and heats it while you use it. When you open the tap, the hot water already in the tank comes out first, and the element keeps heating the fresh water that follows. You never use water as hot as the tank, because you mix it with cold water. So the tank gives you more than its size at a comfortable temperature, and the amount depends on how cold your tap is.

Worked example: the tank is set to 55 degrees C, you use the water at 40 degrees C and no heat is lost. The sum is capacity x (55 minus tap temperature) divided by (40 minus tap temperature).

So a full 3L tank gives you about 5 litres of comfortable water at once, and a 5.5L tank gives you about 9. After that, you wait for the element.

How long you wait after the tank is used

Both sizes have a 3000W element. At that power, water warms by 25 degrees C (from 15 to 40) at about 1.7 litres a minute, or about 35 seconds a litre. This is the same for a 3L geyser and a 5L geyser, so the bigger tank gives you a head start, not a faster heater. The table shows the extra wait after the stored water runs out, for a tap at 15 degrees C.

Worked example at 3000W with no heat lost. Real heating takes a little longer.

A 5L geyser makes the biggest difference for the middle task, such as a sink load or a quick wash for two.

Which size for a kitchen sink?

For one sink and one person washing up, the 3L is enough. A few vessels need about 5 litres, and a 3L tank covers that without a wait. Choose the 5L if two people wash up one after another, or if you also fill a bucket for the floor. For the full kitchen line-up, see our top 5 instant geysers for the kitchen and why a kitchen needs an instant geyser. The Aquapro at Rs. 2,499 is the simple answer for one sink, and the Primus at Rs. 3,810 suits a kitchen in a tall building, as it is rated up to 8 bar.

Which size for a wash basin?

A wash basin or a utility sink needs little hot water, so a 3L geyser is enough in most homes. The Instaflo Neo at Rs. 3,199 and the Instaflo at Rs. 4,430 carry a 6 year tank warranty, which suits a geyser that runs every day. If the same geyser also serves a nearby kitchen sink, step up to a 5L.

Which size for a small bathroom?

A shower at about 6 litres a minute needs around 10.5 kW to warm the water by 25 degrees C, and a 3000W element supplies 3 kW, which is under a third of that. So neither size runs a shower. What a 5L geyser does well is a bucket bath. A full 5.5L tank gives about 9 litres of comfortable water at once, and the element supplies the rest at about 1.7 litres a minute.

For a small bathroom with a bucket and mug, the Aura Rapid Pro at Rs. 3,699 is made as a bathroom geyser, and the Calidus Pro at Rs. 3,349 is the lowest-priced 5L. If anyone wants a real shower, choose a storage geyser. See our 10 litre geysers and the comparison of instant and storage geysers.

Wall space and weight

A 5L geyser is a bigger object. The Rapidus 5.5L measures 30.7 x 28.2 x 52.5 cm and weighs 3 kg empty, while 3L models such as the Instaflo (18 x 18.6 x 34 cm, 2.1 kg) and the Instaflo Neo (23.8 x 19.8 x 35.5 cm, 2.25 kg) are far smaller. Add the water and a full Rapidus carries about 8.5 kg on the wall, against about 5 kg for a full 3L geyser. Check the wall, the clearance above the unit and the position of the pipes before you choose. A hollow or panelled wall needs extra care, so ask the technician to check it.

Winter use and building height

In winter the tap water is colder, so the table above applies at its low end: about 4.5 litres from a 3L tank and about 8 litres from a 5.5L tank at 10 degrees C. Colder water also takes longer to heat, from about 35 seconds a litre at a 25 degree rise to about 42 seconds a litre at a 30 degree rise. If your winters are cold, lean towards the 5L, or towards a storage geyser for the bathroom. Our winter heating bill tips help you keep the running cost down.

For pressure, the 5L geysers are rated up to 6.5 bar, which suits low and mid rise buildings. Among the instant geysers, only the Primus 3L is rated for 8 bar. If you live in a tall tower and want an instant geyser, read our guide to geysers for high-rise buildings first.

Which model fits which case

Frequently asked questions

Q: Is a 3 litre geyser enough for a kitchen?

A: Yes, for one sink and light use. A few vessels need about 5 litres of warm water, and a full 3L tank gives about 5 litres at a comfortable temperature. If the sink is busy through the day, the 5.5L geysers give you a bigger head start.

Q: Is a 5 litre geyser enough for a bathroom?

A: For a bucket bath, yes. A full 5.5L tank gives about 9 litres of mixed water at a 15 degree tap, and the element supplies about 1.7 litres a minute after that, so a 20 litre bucket takes about 6.5 extra minutes. It is not meant for a shower. Choose a storage geyser for that.

Q: Which heats faster, a 3L or a 5L geyser?

A: Neither. Both use a 3000W element, so both warm water at the same rate. The 5L takes longer to heat a full tank, about 5 minutes against under 3 minutes for a 3L from 15 degrees C to 55 degrees C. What the 5L gives you is more hot water ready at the start.

Q: Does a 5 litre geyser use more electricity?

A: Not for the same amount of water. Heating 20 litres from 15 to 40 degrees C takes about 0.58 units, or about Rs. 4.65 at Rs. 8 a unit, whichever size heats it. A 5L geyser draws the same 3 kW while it runs. See how geyser power consumption is calculated for your own tariff, and 2kW vs 3kW geysers for what the 3 kW load asks of your wiring.

Q: Can a 3L geyser run a shower?

A: No. A shower at about 6 litres a minute needs around 10.5 kW to warm the water by 25 degrees C, and a 3L geyser has a 3 kW element. It is made for a sink, a basin or a small bucket.

Q: What pressure rating suits each size?

A: The 3L geysers are rated up to 6.5 bar, except the Primus at up to 8 bar. All three 5L geysers are rated up to 6.5 bar, which suits low and mid rise buildings. Read how to use a geyser safely before you install.

See all 3 litre geysers, all 5 litre geysers or every instant geyser in one place. Our geyser buying guide walks you through the other decisions, and the geyser capacity guide covers the bigger sizes.