The Rainbow RainMate air purifier was invented as part of a patent developed by Rexair in 1988. That patent expired in 2006, so the market is now full of these “water air purifiers” that allegedly afilter air through water to remove pollutants.
While the primary market for this invention was a new type of vacuum cleaner, Rexair decided to use this technology on a smaller scale as part of an air cleaner. However, the Rainbow RainMate air purifier is not sold directly to the consumer. Instead, it’s used as part of a home sales presentation where a salesperson would try to sell a $3000-$4000 cleaning vacuum system while gifting or heavily discounting the price of the Rainbow RainMate along the way.
I’m not a fan of direct selling, as it naturally disadvantages the consumer, who will feel pressured to purchase something with someone in their home. Thankfully, I didn’t have to sit through a presentation for my Rainbow RainMate.
We bought the Rainbow RainMate with our own money and tested it to assess its air cleaning performance, energy efficiency and sound generation. You can read more about our air purifier testing process, but in short, we gather comparable data to help consumers compare and contrast the minefield of air purifiers on the market.
We don’t run ads on our site and are independent, so we are free to say exactly what we think about the air purifier we review. Unlike most sites that review air purifiers, we regularly share devices that fail to live up to the hype or those that should be avoided.
The lowdown on the Rainbow Rainmate
The Rainbow RainMate has not associated filter costs, but it failed to complete our particle removal test.
After testing this device, it is my opinion that this is a pretty-looking fragrance diffuser, but it shouldn’t be considered an air purifier.”
If you don’t want to read my 2000-word review on this air purifier, then you can see my key points below:
What we really like
What we think could be better
| HouseFresh rating: | ☆☆☆☆☆ (if we could give it negative stars, we would) |
| Time to clean our 728 cubic feet test room (with the device running at top speed): | It was unable to clean our air in our test |
| Air filtration technology: | Water |
| Recommended room size (4.8 air changes per hour): | The manufacturer states 1200 sq. ft., but it will not be able to clean the air in even the smallest of rooms. |
| Clean air delivery rate (CADR): | Not available |
| Dimensions (in inches / in cm): | 9H x 8W x 9D inches (22 x 20 x 22 cm) |
| Weight (in pounds / in kg): | 2.8 lbs (1.2 kg) |
| Filter life: | No filter, but the water needs to be changed |
| Noise level in decibels (measured from 3 ft. away with a sound level meter): | 53.3 dB |
| Electricity consumption in watts (recorded with an electricity usage monitor): | 10.8 watts |
| Estimated running cost (electricity consumption + official filter replacement): | $11.35 per year |
| Manufacturer’s warranty: | 4 years |
| Country of manufacture: | United States |
At HouseFresh, we have tested over 105 air purifiers and recently put together our list of the best cheap but great air purifiers. We also have small air purifiers for those who want something that doesn’t take up too much space and would make a great alternative to the Rainbow Rainmate.
Looks more like a coffee machine
The Rainbow RainMate looks more like a coffee maker than a standard air purifier.
It’s small and easy to use, and you can easily keep it on top of furniture. The design is pretty minimalist with a blue bowl for the water and a top you can unscrew to replace the water. On the top, you will also find one button with two modes: one to turn on the RainMate (one line) and another to turn on the LEDs (two lines).
This simple control panel makes the Rainbow RainMate incredibly easy to use.
You just need to switch it on when it’s full of water by pressing the button with one line ( – ), and the RainMate will start pulling air from outside into the main tank, causing the water to start bubbling. If you want to add some color to the experience, you can turn on the LED light by pressing the button with two lines ( = ).
The main tank needs to be filled with water before you can use your Rainbow RainMate, and this is also easy. Make sure to unplug the device before you unscrew the top cover, using the handle clockwise to reveal the opening of the water bowl.
As I mentioned earlier on in the review, I think the Rainbow RainMate is a nice air freshener. You can actually add fragrances to the water for aromatizing or deodorizing the air. The manual of the device clearly states that one should only use Rainbow brand fragrances in the RainMate as other oils and liquids could cause damage — I haven’t tested this, so I can’t confirm whether this will be the case.
Before you plug and turn on the RainMate, you need to make sure the top is fully closed and that it doesn’t tilt or move when sitting on top of the water bowl.
Water filtration technology
No need to replace particle or gas filters with the Rainbow RainMate — too good to be true?
Unlike the standard air purifiers we review here at HouseFresh, the Rainbow RainMate uses water as the filter. The water will need changing when running the unit for a long time, but this will not incur additional long-term running costs compared to normal air purifiers with activated carbon and HEPA-like filters.
I have read many academic studies that support the excellent performance of HEPA filtration at removing particle pollutants. I’ve also read papers and studies supporting the performance of activated charcoal at clearing gasses from the air. However, I have never seen any studies supporting the technology used in the Rainbow RainMate or proving the power of water to remove particles and VOCs from the air.
The reality is that no one likes having to purchase new filters every six months, so water-based air filtration sounds like the perfect solution. That said, at this stage (and considering the performance of the Rainbow RainMate and similar units in our tests), I think this just sounds too good to be true.
The Rainbow RainMate was unable to clean the air in our test room
The RainMate took so long that the phone I use to record the particle removal test ran out of battery.
We started our test in the same 728-cubic-feet room where we tested all of our air purifiers, filling up the room with incense smoke at 2:11 p.m.
We switched the Rainbow RainMate on at 2:42 p.m. and then tracked the levels of PM1, PM2.5 and PM10 particles in the air with our air quality sensors from PurpleAir. We also filmed the test so our readers could see how well the device removes particles from the air in real time.
You can view the video below:
Most particle removal tests are completed within 60 minutes, although some smaller devices can take double the amount of time. For example, the like the Levoit Core Mini took 113 minutes.
In the case of the Rainbow RainMate, the results were even worse.
For starters, at 5:25 p.m. my iPhone ran out of battery, so the test continued without being filmed. This was 163 minutes after 2:42 p.m., which was the time when I switched on the device.
However, the experiment continued until 6:03 p.m. At that time, I made an executive decision to end the test. At that point, the level of PM1 particles was still at 20.14 and any further reductions would just be down to the natural ventilation in the room.
Even after 3 hours and 35 minutes, our test room was still polluted with tiny particles.
Based on the 70+ air purifier performance tests we have completed so far, the Rainbow RainMate sits at the bottom of our leaderboard as it was unable to clean the air in our test room. The only other device we tested that was unable to remove all PM particles was the infamous Sharper Image Ionizer Breeze from 10+ years ago.
Air cleaning performance, compared
You can see here how the terrible performance of the Rainbow RainMate Water Air Purifier compares to other low-budget units on the market:
We even compared it to devices like the IQair Atem Car, which is designed to work inside a car cabin, and the Rainbow RainMate still trailed far behind them.
The fact that this unit is touted as suitable for asthmatics and allergy sufferers is not true. This device will not be able to remove pollen and dander quickly enough to avoid triggering allergy/asthma symptoms.
Considering that Rainbow RainMate was unable to remove incense smoke pollutants, I know it will be useless against real-world issues such as wildfires or cigarette smoke, both of which create many more pollutants.
Noise levels, compared
We recorded the noise levels generated by the Rainbow RainMate using a sound monitor from three feet away. While the sound is less intrusive than a standard fan, it still hits 53.3 dB, far from the silence touted in its marketing material.
This is how this compares to other small devices and some of the loudest we’ve tested:
The cost to run a Rainbow RainMate: $11.35 per year
1. Electricity costs = $11.35 per year
As with all the air purifiers we have reviewed here at HouseFresh, I used an energy meter to measure how much electricity the Rainbow RainMate pulls when running.
The Rainbow Rainmate pulled 10.7 watts without the lights running and 10.8 watts with the lights running.
| Electricity consumption with light off | Electricity consumption with light on |
| 10.7 watts | 10.8 watts |
2. Filter costs = $0 per year
As this air purifier uses water to filter the air, there are no extra filter costs to consider, as you just change the water every few weeks.
Bottom line: Is the Rainbow RainMate worth it?
You often hear the phrase, “It sounds too good to be true,” and for the Rainbow RainMate, this might be the case.
After testing the Rainbow RainMate, it is my opinion that this is a pretty-looking fragrance diffuser, but it shouldn’t be used as an air purifier — especially not one to be used to help ease asthma and allergy symptoms. Our particle removal test showed the Rainbow Rainmate will not be able to clear the air of pollutants that trigger allergic symptoms.
Some of our YouTube viewers who have the Rainbow RainMate reported they enjoy the relaxing sound of the water twirling around inside the bowl and that they like the mood set by the LED lights. I agree with them that this is a cute water whirilpool thingy, but please don’t get confused to think this is an air purifier.
If you are trying to buy a small air purifier, I would suggest you look at the Winix A230 instead or the even smaller Smart Air QT3. You will have to accept that you will need filter replacements every few months, but in exchange, you will be confident that it is cleaning the air in your home.
But if you want a water fragrance diffuser like the RainMate, you will be able to find one on eBay and you can also get a generic version on Amazon. I would suggest you don’t accept salespeople in your home as I have read that the RainMate is often offered free or as a “prize” if you agree to a salesperson visiting your home with the goal of hosting a presentation to sell you a higher-priced vacuum cleaner ($4,000).
Now, I have written quite a few negative reviews of air purifiers over the last few years, but I have never received as many irate emails as I did when my video review of the Rainbow RainMate went live.
Most consumers will just feel a little embarrassed that they bought a sub-par product and will email me to ask for a recommendation that will not break the bank after they have already invested in a bad device. But in the case of the comments and emails i received about the RainMate, I wonder if these are not customers but people using the RainMate as part of their sales pitch for other products.
So I went over to Reddit to dig a little deeper and was shocked at the number of people talking about the Rainbow “Fresh Air Machine.” From reading many threads, it’s clear that the RainMate is being used as a hook to get salespeople though the door as part of a high-pressure in-person sale opportunity.
I would have hoped that the invention of the Internet would make this type of in-person sales technique obsolete, but unfortunately, that doesn’t seem to be the case. I hope this review will provide more insights to people who are feeling the pressure to get this product.
If you found it helpful, be sure to share it with your friends and on social media.
SOURCES
We used the Department of Energy’s appliance energy calculator to calculate the yearly electricity costs associated with running the Rainbow RainMate for 24hs a day for 365 days. We ran this calculation utilizing the U.S. average utility rate of $0.12/kWh as of May 31st, 2024.
Thank you for making many aware of products that can be misleading. It does look pretty.
Thank you! As long as it is not sold as cleaning the air, there can be a place for a device like this.
Danny Ashton is 100% spot on with everything he has reviewed about the RainMate. It could be used as a diffuser, but that’s about it. It is only used as a gimmick for the salesperson to come to your home to sell the 4,000-dollar Rainbow vacuum and then will attempt for you to sell the same item to your unsuspecting friends with a so-called “ride along”. This is direct selling (MLM), even though the salesperson will deny it. Please DO NOT buy the Rainbow vacuum because you will regret it. No vacuum is worth 4K. The salesperson will attempt to tell you that it outperforms HEPA filters, but that is a lie. The salesperson will attempt to lead you to believe that all traditional vacuum cleaners will only re-introduce dust and other pollutants back into the air. The salesperson conveniently neglects to say that the Rainbow vacuum is also outfitted with a HEPA filter (one that is very expensive to replace). Even if you return the Rainbow vacuum within the 10 days as outlined in the Consumer Protection Act (and clearly stated on their sales contract), they will still attempt to keep your money through unscrupulous methods. Customer service is practically non-existent. Emails won’t be answered, phone calls won’t be returned, and when someone does answer the phone, they only provide vague responses. They will say there is nothing they can do, see if something can be done (but never do), or say that anyone with authority in any decision-making capacity isn’t available because they are not in the office or attending a meeting. In conclusion, if anybody tells you about the Rainbow vacuum, RUN (and save your money and sanity).