Back in February 2016 we glowingly and optimistically ran an article with the headline “Self-Filling Water Bottles Will Soon Be An Awesome Reality.” At the time, the source of our optimism was an IndieGoGo project by the name of Fontus. We were excited by this seemingly futuristic development, and we certainly weren’t the only ones, with many other sites also excitedly reporting on the self-filling Fontus bottle.

In no doubt largely thanks to this media attention, the Fontus bottle’s Indiegogo raised just shy of $350,000 – a small fortune by any standards – yet over a year later, no self-filling Fontus bottles have been seen anywhere aside from promotional videos. Meanwhile, savvy minds with much more skepticism than we had back in ’16 have been examining the claims of the Fontus bottle from an engineering perspective. And they’ve found them lacking.

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Why The Self-Filling Fontus Bottle Just Doesn’t Work

If you take a look at how the Fontus bottle advertises its ability to pull water out of the air, it might seem logical enough to the layman. All the Fontus bottle really claimed to be was a small dehumidifier: drawing air into the bottle and capturing the moisture via condensation as the air cools, using a small solar panel to power the process.

We all know dehumidifiers work, so it seems simple enough, almost a “why didn’t I think of that?” moment when the simplicity of it is revealed. The Devil is in the details. In the video below, Dave from EEVblog decides to run the numbers on the Fontus bottle to figure out just how efficient it might be in the real world. He quickly cuts to the heart of the issue: energy! It takes quite a bit of power to run a dehumidifier.

According to Dave’s calculations, to produce 0.5 liters of water in 1 hour as the Fontus claims, it would require a 250 watt solar panel with 1.5 square meters of surface area operating at 100% efficiency! This is a huge, roof-top style sized solar panel – definitely not the tiny little panel the Fontus is supposed to be equipped with, which is less than 1/6th the size of the panel Dave calculated as being required. Not only that, Dave’s calculations were done for a perfect system, not taking into account real world variables and fluctuations.

In the latter part of the video, Dave takes a look at some of the market-leading dehumidifiers to see how much moisture they can remove, finding a market leading example, the Ivation IVADM10, which only extracts a measly 6 ounces of water per 24 hours of operation. The Fontus claims to be capable of extracting up to 17 ounce per hour, while using substantially less energy than a dehumidifier and being powered by a tiny solar panel. Hang on a minute…

Be sure to watch this full video, and thanks to Dave from EEVBlog for taking the time to do the math!

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So What Gives? Scammers Or Dreamers?

The ultimate verdict reached by those with a skeptical engineering approach to the Fontus Bottle’s claims seem to be more or less the same: you could make the device as advertised. It would make water, and do what it says – but it would do it orders of magnitude less effectively than claimed. Instead of getting a full bottle’s worth of water in about 2 hours at “optimum efficiency,” you would be more likely to get maybe an ounce or two of water throughout an entire day’s worth of sunlight.

It is unlikely in the extreme that Fontus is hiding some kind of remarkable new development that would radically improve the efficiency of any of the technologies they are using to create their self-filling water bottles. If they did, they would surely have made a lot of noise about it and be well along in other endeavors, walking through the doors of opportunity opened by their revolutionary developments. Instead we appear to have snake oil salesmen, creating a device that might do what it says it will only in the most remote technical sense.

Sadly, it seems we have been duped. Fontus may well be just another IndieGoGo scam, which has successfully extracted nearly $350,000 from the wallets of hopeful backers. At the bottom of Fontus’ IndieGoGo page, we find the disclaimer that should have warned us all along:

“It is explicitly pointed out that the products which serve as Perks are in the development phase. It cannot be excluded that during the development phase technical, economical or other circumstances arise which may result in (i) a delay of the delivery of the Perk or (ii) the production and delivery of the Perk in a different form as regards functionality and/or design or (iii) even non-production of the Perk. In the latter case there will be no Perk delivered to the Contributor. Contributions will not be refunded. By making a Contribution the Contributors explicitly acknowledge the risks associated with the occurrence of one of the aforementioned events.”

The “perk” in this case being the Fontus bottle itself. Straight from the horse’s mouth: it might not work how we said it would, it might not work at all, we might not even make it, and no, you can’t get a refund.

Some Funny Math

Fontus has made a big deal about its designer receiving a James Dyson award, so we went and had a look on the James Dyson Awards page for Fontus Bottle and under the “Stages of Development” heading we found something odd:

“I conducted a series of experiments trying to identify the ideal conditions, materials and cooling systems. I simulated different climatic conditions in my bathroom, modifying the air temperature and humidity. After more than 30 experiments, I finally achieved a constant drop-flow of one drop of condensed water per minute. After developing a functioning inner system, I designed a compact and practical hull which can be easily attached to a bicycle, integrates the water bottle and can be comfortably handled.”

This quote is from Fontus designer Kristof Retezár and it shows us that, clearly, Fontus must know their bottle is not going to work. Although it is a very vague term Kristof is using, there is a precise measurement for a “drop” of water: in the scientific defintion, a drop is equivalent to 0.05 mL. If Kristof meant a drop in the scientific sense, his device produces about 3mL of water an hour. Over a full 24 hours, that would give us a little less than 2.5 ounces of water, a rate that would take nearly 11 days to fill the 27 ounce Fontus bottle.

This is a pretty huge contrast to the 0.5 liters (17oz) per hour that Kristof claims the Fontus can produce at the top of this very same webpage. If they have increased the efficiency so dramatically, why bother reporting these results of one drop per minute at all?

More Engineer’s Opinions on the Fontus Bottle Scam

Another fantastic YouTube video from user Thunderf00t goes into depth debunking the Fontus bottle, and pointing out some of the more ridiculous aspects of the project in a humorous manner. He also gives a nice little lesson on physics and engineering. Check it out!

In a discussion about the Fontus bottle, reddit user Oznog99 left an informed and enlightening comment on engineering a self-filling bottle with a look at some of the numbers involved. His math seems to agree with some of the numbers laid out by Dave from EEVBlog. Quoted below:

“Engineer here. Lemme give you the practical numbers.
Condensing moisture from humidity into water requires 9000 BTU/gal, if the air’s already at the dewpoint, 100% humidity. 17 fluid ounces requires 1195 BTU to condense.

If this were the efficiency of a central air conditioner, this would use 92 watt-hrs of electricity.
But we’re surely talking about Peltier solid-state cooling, which has not advanced significantly in 25 years or so. If it did, it would be huge news.

Peltiers are like 10th the efficiency of R134a [air conditioning] systems. And the performance curve is really critical- if the heatsink gets significantly warm, the performance drops precipitously. Heatsinks have to be huge to actually dissipate the wattage while not being particularly warm themselves.

So you’d need about one kilowatt-hr to make 17 ounces of water in 100% humidity conditions. Just so you know, a fit person pedaling a generator for long periods without going anywhere will generate about 200W, so you’d need 5 hrs of work.
Solar panel tech is about 14.5 watt per sq ft. So to generate 1KW in 4 hours of decent sun a day, that would require over 17 sq ft [roughly 1.5 square meters] of solar panels to produce the 250W output to condense 17 oz with a Peltier over the course of the day. This doesn’t make a lot of sense, you would not have that much sunlight in 100% humidity conditions.

What that shows is “moisture farming” is fantastically energy-intensive. If you were going to condense water out of the air, you’d use conventional R134a/R410a refrigeration and counterflow heat exchangers. The performance will be an order of magnitude better, but the bottom line STILL makes no sense.

If you had that much power, you’d probably find something better to do with it than making a few oz of water. Water is a thing, but not THAT critical, and if it were, you would not have the means to be doing this sort of huge “solution”. Well if you’re in a desert with no means of support and dying of thirst, yes 17 oz of drinking water is a big thing, but a massive, expensive solar array would not make any sense as a solution. You need far more water than that to live and farm.

In any case, the proposal does not add up. Nothing that size can condense 17 oz of water a day from solar, even under the most ideal conditions, however unlikely they may be.”

We’re Sorry

We’d like to take this opportunity to apologize to all of our readers and especially to anyone who may have sent money to support the Fontus bottle. We reported on it during the height of its popularity and did not do our due diligence to look into the science behind the bottle. The idea of a self-filling water bottle is extremely exciting to us and we were overjoyed to bring the idea to our readers.

It is very unfortunate that it appears the Fontus won’t be living up to its claims. This brief examination of the science also leads us to conclude that anything capable of producing the sort of results the Fontus advertised is a long way off. Harvesting drinking water from the air is a tricky business, not something you can solve by just hooking up a solar panel and a dehumidifier in a bottle.

However, we’re going to keep our eyes on the horizon. Should a self-filling water bottle which is actually practical become a reality, we’ll be the first in line to buy one.

Find A Bottle That Works

If you want a water bottle that actually performs as advertised (although nothing miraculously self-filling,) be sure to check out our Best Water Bottles 2017 article.

We examine why the self-filling Fontus water bottle appears to be a non-starter, debunking this crowdfunding success with a bit of science and engineering.