Blue Diversion toilet is flushed with success


March 12, 2014

The closed-system Blue Diversion toilet is designed for off-grid use

The closed-system Blue Diversion toilet is designed for off-grid use

Image Gallery (5 images)

Two years ago, an off-grid closed-system toilet known as the Diversion won an award at the Bill & Melinda Gates Foundation's "Reinventing the Toilet" fair. Created by the Swiss Federal Institute of Aquatic Science and Technology (Eawag) and now called the Blue Diversion, it recently also won the title of Most Innovative Project (Europe/West Asia), as bestowed by the International Water Association. So, what makes it so special? Well, for one thing, the same water that flushes it is subsequently used in its hand-washing sink.

Here's how the Blue Diversion works ...

Feces, urine, and flush water are separated right below the toilet bowl. The first two items are then stored in sealed compartments, for subsequent use as fertilizer. The water, because it's used more to rinse out the bowl than to actually transport the waste, isn't as contaminated as what goes down a regular toilet's pipes. It's still pretty disgusting, though, so it's pumped into a filtration system in the back wall of the setup.

There, it passes through a bioreactor that neutralizes organic matter and ammonia, along with an ultrafiltration membrane that blocks pathogenic organisms such as bacteria and viruses. Any remaining trace amounts of organic matter and ammonia are then neutralized by an electrolysis unit, which also produces chlorine to disinfect the water.

From there, gravity carries the water down to be used in the sink, in a bidet-style shower head, or to rinse out the bowl once again. According to Eawag, the same water is good for about 50 uses per day. Power for the pumps, electrolysis unit and electronics are provided by a top-mounted photovoltaic panel.

Although the whole water-reuse thing may still sound kind of ... yucky to some people, the Blue Diversion has reportedly been successfully field-tested in Uganda and Kenya. Eawag is currently looking for industrial partners to help with large-scale production, and hope to sell it for use in developing nations and off-grid locations for about US$500 per unit.

... and should you not be into squatting, a sit-down version is due to come out next year.

Sources: Eawag, Blue Diversion

About the Author
Ben Coxworth An experienced freelance writer, videographer and television producer, Ben's interest in all forms of innovation is particularly fanatical when it comes to human-powered transportation, film-making gear, environmentally-friendly technologies and anything that's designed to go underwater. He lives in Edmonton, Alberta, where he spends a lot of time going over the handlebars of his mountain bike, hanging out in off-leash parks, and wishing the Pacific Ocean wasn't so far away. All articles by Ben Coxworth

Storing the water in a clear tank out in direct sunlight would reduce the need for equipment to kill bacteria.

Gregg Eshelman

If the same water is only good for 50 uses per day, then that implies the process is not a 100% in removing the yucky stuff!

Best to be first inline rather than number 49!

Brian M

I think I might prefer the windows to be translucent instead of transparent, but that is probably an 'age' thing on my part.

If it only hinders the spread of diarrhoea and the infant mortality that results, then good luck with it. I would have thought that the UN might consider their forming part of emergency provision at disaster sites, where a lack of basic hygiene facilities is often a cause of the spread of disease, which often proves fatal. Though I can see maintenance being a problem.

Mel Tisdale

I think that is great for places with poor hygene. It is not perfect but it is better than what many places have to deal with.

I think it would also be great for places that are off grid; camps, tiny houses, etc.


Very interesting. I would love to hear more about the specs-i.e. power, water use per flush (even averaged over 50 uses), dimensions, etc. This has the potential to be very useful to North American market on homes and building that are looking to become net zero in water. Average North American water use per person is 75 gal/day, 35% of which is due to our unsustainable toilets.

Currently, the only other approach that addresses the "yuck" factor of composting toilets is a Clivus Multrum foam flushing toilet(, which is costing upwards of $10,000 per unit!

Thank you for this inspiration David


I think this both a dangerous and ridiculous idea. While we are struggling to cope with MSRA and a host of other bugs which, they claim, are mainly transmitted by unclean hands, this idea is purported to be a great step forward? Gee, give me the money! If they wished to fulfil this idea as a working project, why not collect (contain) the previous person's hand wash, to flush away the following user's waste? i.e. No bio-filtration etc. would be necessary, the flushing water could be primed for use at any time, even by a hand wash of the toilet installer. As this currently reads, a crazy idea and a dangerous waste of money. (IMO)

Jerome Thomas

Calm down experts, as if Bill Gates didn't consider such an obvious risk. The website says the problem is a build-up of salts in the water, a common problem also in drinking water .


I still would prefer to be #1-5 rather than #49-55! They say it is good for "up to 50" - does it then close down till it is serviced? A version that does the handwash bit as first use of the water sounds better to me. That way the flush tank would be topped up by that and bio-treated water for use at the end of the process.

The Skud

@ Brian M That's just a reflection of it taking about a half hour to recycle a given parcel of water each time. Not an indication the the water is getting ever dirtier. . .


I feel that the disposal of human waste is one of the most important issues facing civilization. Our aversion to admitting we pee and have BMs has some very serious consequences. Putting waster water and feces into the some water treatment systems over loads the systems and causes the contamination of our oceans. Every large rain results is some areas having sewage spills into the ocean and some have caused flesh eating bacterial infections. Not interested. You might be if you go into these contaminated environments and come out with an infection that takes your life.

Ouida Trahan
Post a Comment

Login with your Gizmag account:

Related Articles
Looking for something? Search our articles