Is RO water better than tap water for a diffuser? Yes. Tap water, especially hard water, carries minerals that settle as white dust and scale. RO water has far fewer, so it keeps both the air and the machine cleaner.
What do I add to the RO water? A few drops of SOSA's water-based Hotel Collection fragrance. That is all. Raw essential or carrier oils are too thick and can clog the misting plate, whatever the water.
Why RO water is the cleanest choice
The advantage of RO water is entirely about what is not in it, and that turns out to matter a lot for an ultrasonic machine.
Compare that with hard tap water, which carries calcium and magnesium that the mist scatters as a pale film nearby and bakes onto the plate as scale over time. RO water simply sidesteps both problems, which is why I call it the ideal choice rather than merely an acceptable one.
My honest note: filtered water from a good home filter is nearly as clean as RO for this purpose. The point is low minerals, so either works well. It is hard, unfiltered tap water you want to avoid in a hard-water city.
How to use it well with SOSA fragrance
Using RO water well is straightforward, and it makes the water-based fragrance shine because nothing competes with it in the tank.
Fill with room-temperature RO water. Straight from your filter is fine. There is no need to warm it, and you must not: the machine is cool mist and hot water is never appropriate.
Add a few drops of water-based fragrance. A little goes a long way. Because the water is clean and the fragrance is made for water, it disperses evenly and the plate stays clear.
Enjoy the lighter maintenance. With RO water you will find you descale far less often. A rinse every couple of days and the occasional vinegar descale is plenty, rather than a constant battle with scale.
The worry: "RO water is too pure and might harm the diffuser." It will not. Low-mineral water is exactly what an ultrasonic plate likes; the machine mists it happily and stays cleaner for it. There is no downside to RO water here, only benefits.
Use only SOSA's water-based Hotel Collection fragrance in these diffusers. Raw essential oils, perfumes and carrier oils are too thick or solvent-heavy, so they can clog the ultrasonic misting plate and damage the unit. Fill with clean, room-temperature water (filtered or RO in hard-water cities to avoid mineral white dust), never hot water. The mist is cool, with no heat, and it scents a room rather than purifying the air.
The SOSA range
SOSA makes three cool-mist ultrasonic diffusers for different rooms, each arriving with three of our water-based Hotel Collection fragrances so you can scent from day one. Prices and headline specs below are live from the SOSA store. Whichever you choose, use only the SOSA water-based fragrance - raw essential or carrier oils can clog the misting plate.
| Diffuser / refill | Character | Best for | From |
|---|---|---|---|
| Boond (300ml mini) | USB · up to 6 hrs · colour night light · ~150 sq ft | Desk, bedside, hostel | ₹799 |
| Sukoon (500ml) | 16-18 hrs · 7-colour LED · remote + 2H/4H timers · 270-320 sq ft | Bedroom, study, nursery | ₹1799 |
| Megh (6L) | Up to 100 hrs · adjustable mist dial · ~35 dB · large-room humidifier | Living room, dry AC, winter | ₹3499 |
| Hotel Collection fragrance | Water-based refill · 7 hotel-inspired scents · 15/100/300ml | Refill for any SOSA diffuser | ₹299 |
Versailles
I trained as a perfumer at ISIPCA in Versailles, but half the questions we get are not about scent at all - they are about the machine. Indian rooms are bone-dry from AC and winter, and most gadget diffusers are too small, too loud, or quit by midnight. So we made three: Boond (300ml, desk), Sukoon (500ml, bedroom, with a remote and mood light) and Megh (6L, whole-room), each shipping with three of our fragrances.
They are cool-mist ultrasonic diffusers - an ultrasonic plate turns water into a fine, cool mist with no heating element, so there is no boiling water or burn risk, and each has an auto shut-off when the tank runs dry.
One thing I say on every listing and will say here: use only SOSA's water-based Hotel Collection fragrance. Raw essential oils, perfumes and carrier oils are thick or solvent-heavy and can clog the misting plate and damage the unit. A few drops of our water-based fragrance in the tank mists cleanly and scents the whole room.
Frequently asked questions
Facts verified June 2026: SOSA makes three cool-mist ultrasonic diffusers: Boond (300ml, USB, colour night light, up to 6 hrs, ~150 sq ft, ₹799), Sukoon (500ml, 7-colour LED, remote + 2H/4H timers, up to 16-18 hrs, 270-320 sq ft, BPA-free, ₹1799) and Megh (6L, adjustable mist dial, ~35 dB, up to 100 hrs, ₹3499). Each is cool mist (no heating element) with auto shut-off, ships with 3 water-based Hotel Collection fragrances (15ml ₹299 / 100ml ₹999 / 300ml ₹1799), and is made for Indian AC-dry and winter air. Use SOSA water-based fragrance only; raw essential or carrier oils can clog the ultrasonic misting plate. Composed in India; a portion of every order supports Nanhi Kali girl-child education. These are independent, hotel-inspired fragrance interpretations created by SOSA. SOSA is not affiliated with, endorsed by or associated with the hotels named; all hotel names are trademarks of their respective owners and are used only to describe the scent style.