Bag of Happiness

Life Lived to the Edge of Possibility

David Kinne

David Kinne
Volcano, Hawaii, USA
June 15
Founder & President
La Vida Buena Partnership
David Kinne is the possibility of people living extraordinary lives of creativity, joy and full self expression. He has led over 2,000 seminars in 6 countries. He is currently working to complete a book of his photos and text about life lived fully called "Mysteries/Answers"


SEPTEMBER 9, 2010 1:29PM

Ecosan - Ecologically Sound Sanitation - SOHIAC #5

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Ecosan bathroom

 Slice of Heaven in a Can (SOHIAC) is my project to develop an inexpensive, minimalist solution to the issue of homelessness due to disaster or societal conditions, by reusing surplus ISO shipping containers as a basic construction module.  

Since Roman times, and perhaps before, water systems have been used to carry away human waste. A significant infrastructure to deal with sewage is part of every major city’s operations and budget, and most of them rely on water transport through a system of sewer pipes to deliver the sewage (or Blackwater, as it is also known) to a large scale plant for neutralizing the health hazards and turning it into a safe sludge that can be recycled as agricultural fertilizer.  

When that infrastructure is not in place, or when it is not functional, things can get quite horrendous very quickly, as witnessed by Emily K. Troutman, in this firsthand account from Port Au Prince, Haiti: 

Off the grid, we have to deal with sewage without the urban infrastructure, so what to do? In the illustration at the top I depict what is probably the most radical, and almost certainly the most controversial aspect of my SOHIAC design. Some readers, predictably, will not make it through this entire article. What you see above is the entire SOHIAC bathroom… a composting toilet inside a shower stall.

Let’s look at the toilet first. Everybody poops, everybody pees. What do you do with it? With a standard American water closet you push the handle and a couple of gallons of water flush it all down into the sewer system (aka “Flush & Forget”). This is the largest single use of water in a typical American household, and the average American flushes away about 7,750 gallons a year. In rural areas, the septic tank and field are the norm for disposal, but still using that same amount of flushed water, which must be dispersed safely, somehow. First I’ll discuss the traditional septic system, and then explain how a newer “Divide & Conquer” approach is more ecologically sound.

Septic Tank

What happens in a septic tank is that the water is separated from the solids, which begin being digested by anaerobic bacteria and settle to the bottom. The excess liquid overflows into a second tank, in which further digestion and settling occur. The relatively clear water overflowing from the second tanks flows out to an absorption field, commonly known as a leach field.

septic leach field

In the leach field, the liquid flows through perforated pipes into gravel filled troughs, and from there leaches out into the surrounding soil where it is taken up by plants and trees. As Erma Bombeck famously wrote, “the grass is always greener over the septic tank,” because it is receiving underground water and fertilization from the leach field.

The settling tank in the septic system fills up eventually, and must be promptly pumped out, or the solids will overflow into the leach field and ruin it. And there must be adequate clear ground and a reasonable percolation rate (absorption rate of the soil) for it to work. Absent either, the next choice is a cesspool, in which waste is merely stored until it can be pumped out. A PortaPotty is essentially a portable cesspool. Absent a cesspool, you are back to digging a hole in the ground, and covering it over when full, an even more smelly and unhealthy alternative.

Composting toilets are a relatively new development in which that whole process is compacted into a single appliance. Waste goes in, and dry, odorless composted fertilizer comes out. Canadians and Scandinavians have taken to composting toilets in larger numbers than Americans to date. Ecological activist and actor Ed Begley, Jr. is probably the best known user, endorsing the Envirolet composting toilets which are installed in his Beverly Hills home, and fertilizing his lush rose garden with the output.

EnviroletOf the three most widely available brands in the US, Envirolet is the Cadillac. It’s also the largest unit, and the most expensive, and has the most options.


Biolet 30 NEBiolet is a little smaller, a little less expensive. But both are about twice the size and 50-100% more expensive than the unit I’ve chosen for this project, the Nature’s Head.

Nature's HeadIt’s so called because it was designed as a “zero discharge” head (toilet) to be used in the confined quarters of a boat, and it’s a US Coast Guard Approved Class III device. It’s also American made, whereas the Envirolet is Canadian and the Biolet is European. It is manually operated, except for a small exhaust fan. I'll use a solar powered fan for this application. 

I’ve compiled the most pertinent details below, and you can find out more about all of them on the internet. A European brand, Separett, has an innovative design that would make the cut if it were more readily available in the US; however at this writing its US website is down and I can’t get any current info on it.

Brand, Price,  Shipping (to Hawai’i), Volume Occupied cu/ft,  Notes

Envirolet Basic Plus, $2,099 , $290, 11.9 cu ft ,Water flush models, vacuum extraction, remote storage, you name it, great if your budget is unlimited

Biolet NE, $1,300, ~$250 , 6.6 cu ft , Good quality, good reviews, but seems to have a serious customer service issue, based on internet comments.

Nature’s Head, $885 , $150 , 3.3 cu ft , Ships direct from Ohio factory. Simple, effective, fits in smallest space.  Dual waste system.

Comparison made on non-electric base models with comparable features, with capacity for 2 adults in full time usage.

Single Stream or Divided Stream? – Water based sewage systems are “Single Stream,” with all waste being combined in one sewer pipe system. It’s efficient for large scale urban systems, less so for rural systems, because the first step in the process is to separate liquids from solids. An old idea, Divided Stream Waste, used in Queen Victoria’s royal toilet, has been reinvented for Ecosan purposes.

The principle is simple. Solid waste (the poo, if you’re having trouble following this) needs to be liquid free, merely damp, in order to compost aerobically and thus destroy disease causing organisms. Urine, on the other hand, is inherently sterile, and in addition is a safe, nitrogen rich fertilizer when diluted. (See the book “Liquid Gold” for details.)

Conventional composting toilets are single stream, combining liquid and solid waste, primarily using fans to dry the waste to proper composting moisture levels. Dual stream composting toilets separate the urine at the source, for disposal in a simple “greywater” system designed to disperse shower and sink wastewater. Properly designed, this can be used advantageously for garden irrigation. And once the solid waste is fully composted, it is an odorless, nearly dry soil amendment for rich lawns and flower beds. It can also be added to a conventional compost pile where it works as a starter and accelerant.  

Now, back to the mini-bathroom concept. In a 160 sq ft efficiency apartment, it’s important not to devote too much space to the bathroom, and combining the toilet and shower in one 3’ x 4’ stall is about as compact as I can make it and still retain utility. Having a shower head on a flexible hose and a floor drain in the middle means that cleaning up the entire bathroom space is simple and easy. And having a seat and a grab bar in a shower stall is extremely practical, allowing seated showers, easy grooming of legs and feet, and good safe access for the disabled and elderly.

Bathroom and galleyThe sink, since you were wondering, is just outside the bathroom stall in the galley area. For such a compact and inexpensive living space, eliminating the duplication of a second sink only a few feet away makes good practical sense.


Love, David


SOHIAC illustrations and text © 2010 David Kinne.

Search on SOHIAC for other posts in this series. 

Photos courtesy their respective manufacturers. Septic tank and leach field illustrations © Daniel Friedman

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How informative..we have 80 acres up north of here and have no home there or! The plan is to have one someday. I have looked into some of these posibilities for the future. Right now I dedicated an old toilet seat and large plastic bucket with a hole, will do for now! Tx for this!
David, quite brilliant once again... but if you don;t mind I shall go to my own porcelain thronw and worship it for all that it is.:)
Rated with hugs
Great idea! Will you fund your project out of pocket, or are there grants available. Good luck.
I understand that, in a pinch, one can do a single stream composting toilet using a 5 gallon bucket and peat moss/sawdust. This version looks a lot more sanitary, though.
You are quite the scientist and thinker, David. I am awed by inventive minds. I read this with interest because it is such a different topic.
Conrad - The prototype will be self funded as a proof of concept. I think it will be much easier to talk about this to the various authorities and possible funding sources once there is an actual finished unit to look at.

Owl - Yes, sawdust or peat moss are commonly added to composting toilets to supply the necessary carbon for the aerobic composting process to work properly, just as one adds wood chips or tree branches to a gardening compost pile. With the Nature's Head, you prime the system with 2 quarts of peat moss to begin. The down side of using a bucket is that it is hard to get it dry enough and to keep the contents stirred enough for aerobic composting to work. The commercially made units, when properly maintained, are as odor free as a flush toilet.
This is fabulous. What a blessing this would be to people all over the world who live in shacks with NO shower/toilet. I think of all my conveniences those would be the hardest to give up because of the risk of disease.

I especially like that the toilet is in the shower. I'm always freaked out by the area under the toilet that "sweats," it's just gruesome. I'd love to have it rinsed daily, and a place to shave my legs instead of standing like a stork.

Rated for no more hair and dust stuck to the underside of the stool!
Thanks, Bleue. It's nice to know that at least one woman "gets it." A more typical reaction I get is "Ewwwwww." But I think this is a very practical solution, and it serves human needs better than the usual approach for ultra low cost housing, which is to not have a bathroom in the individual units at all. An organization working on the homeless problem in Honolulu is proposing just that, with purpose-built individual 15' steel buildings and shared community bath facilities. At a considerably higher cost per unit, I'd add, and no ecological gain from reusing surplus materials.

Personally, if it's middle of the night and it's raining outside and I need to use the facilities, I'd rather have a clean working mini-bathroom in my unit than dealing with getting dressed, finding shoes and umbrella, etc. I think most people would. I'm sure the guy pushing the other approach would.

This is the gap I see in a lot of thinking about urban planning, and housing design... planners not really putting themselves in the role of the end-user. As I work on developing these plans I'm constantly asking myself "what would work for me?"
Excellent article!

You might wish to take a look at the units presently offered for Motor Homes and small Yachts. My own RV has a combined purpose unit in it that once drained into a "dark matter" tank. I replaced it with a unit made for camping. The drawback is that it must be emptied. I'd love one of the units you've shown here.
Keep us up-to-date on how it's going!!

Having read the book (for pleasure!) BOGS, BATHS & BASINS: THE STORY OF DOMESTIC SANITATION by David J. Eveleigh, I thoroughly enjoyed this post. You are truly
doo doo-ing something to improve this planet.
Mobile Mini is a company that converts containers into security shacks, cosntruction offices, etc. Their supply of containers is fed by our uneven trade balance, i.e., more imports than exports. The excess containers are shipped into the desert to rot. Your project is important and a blessing on several levels. Looking forward to your next installment.

With gratitude,
Thanks, Berean. There are a number of organizations working with the concept, including Affordable Portable Housing in Hawai'i. What I'm trying to contribute is a leaner, greener, less expensive design that might be easily reproduced by others.

In the "Reduce - Reuse - Recycle" ecological mantra, I think Reuse gets the least attention by Americans. But with these surplus ISO shipping containers, cutting them apart to recycle the steel is not cost effective, so they just pile up. Reusing them is pretty much a no-brainer. And in Texas, there is a fairly strong market for them for offices, storage, deer lease cabins, etc. But there is a strong bias against using them for housing. Many HOAs, in Texas suburbs, even in rural Hawai'i, specify that houses must be built of new materials. This is an attitude that will take time to change.
very interestingly detailed r.
Whodathunk I would be riveted by a post about toilets? I hadn't heard about composting toilets either, and I have often wondered what happens after the flush. Thanks for sharing your very interesting project, David.

Wow, I've never given toilets THIS much thought! :)

Our small town's wastewater treatment system used to consist of open lagoons and a sprayfield (the water, after the "solids" had settled, was sprayed out onto a field via an irrigation circle). You can imagine the odor, especially in the springtime when the bacterial process started back up in the stale lagoons. Thanks to a bad winter one year, the lagoons overflowed, and the state insisted we do something. We now have a Biolac system, but the town had to borrow huge amounts of money to install it and our water/sewer prices are really high. I still think it was worth it--you can hang your head over the first treatment pond and not smell much of anything. There is amazing technology out there, as your detailed post points out.

And you're right about the containers--it'll be a while before ordinances change, probably because there isn't much distinction between these things and other kinds of mobile housing (trailers). I think our state has laws about mobile housing that apply statewide.
Won't work. Good for you for being concerned and trying to do something about it. I have reviewed 3 such proposals for Haiti already, all, like yours, by people who don't live with composting toilets.
But here's why it won't work: Those self-contained toilets were designed for cottages, where 1 to 4 people (no matter what the toilet is "rated" for) use the toilet for a few days, then go away. The microbes do their thing, uninterrupted by fresh inputs. And even then, what you remove from these often is not ready for prime time, unless it has had several months to process uninterrupted.

In Haiti, whole compounds will be using toilets. These will overflow. There is no one there to maintain them. Cholera and other diseases are there. For this reason, toilets with much higher capacity and retention time are needed. Look to the systems that are being introduced there with much higher-capacity, either in an aerated vault space or via 55-gallon barrels.
Nature's Head, Airhead, Biolet, Sun-Mar Excel, Separett Villa, and Envirolet XL are made for cottages (and boats, in the case of Nature's Head/Airhead). Until you are in one of these emergency situations, it's hard to imagine the chaos, concentration, disorder, and disease that are there. Scale-up your design. Consider using some existing designs for high-capacity systems.
Good luck!
Thanks for the input, Carol, but you missed a key point that may not have been clear, mentioned earlier in this series. This design project is for a low cost 160 sq ft efficiency apartment for use by 1 or 2 people in the U.S. And the composting units I mentioned can be used continuously, and emptied every couple of months in typical use. Granted, the composting process will not be completed by then, but the contents can be safely added to a conventional compost heap to finish the breakdown.

I referenced Emily K Troutman's article because it details the issues with trying to deal with the sanitation chaos in Haiti, where there was no real infrastructure even before the disaster. Even the Ecosan advocates on the ground acknowledge that a water based system would work best there due to the population density.

There is no "one-size-fits-all" solution. I'm tailoring this particular iteration for a specific target, the homeless of Hawai'i.
Very informative post, I must say. So much to learn on how to deal with the crap on a day-to-day basis. But now you have me thinking about my future posts with things being done in the bathroom - if you get my drift. Rated - Just Jali Smiling.
You really are a resourceful and smart man, David. Very cool project. But, I can't resist saying that it was nice to come here and get a little head....
Your imprimatur means a lot to me, Cartouche. Even rising expectations don't cover up occasional feelings that I'm coming from behind. But your openness to the thrust of the new is encouraging. My lips whisper a thanks. A blessing is on the tip of my tongue. Do come again, whenever you want.
I enjoy these posts about solving problems in such innovative ways and appreciate your efforts to change the world for the corner or flush at a time. thanks David! r
Thanks, PM. I've never thought I could change the whole world. But if I can change the world for one person, is that not worth doing?
david, i make it through. much fancier than the old hoosier outhouses, though somewhat the same principle. just no monkey wards catalog for wipies.
Bea, did you know the old crescent moon symbol on an outhouse originally meant it was for women only?

Yeah, in the internet age paper catalogs are hard to come by, except for the ones from Victoria's Secret, and they're in there for a different purpose I suspect. Of course in Hoosierland, there's no shortage of corncobs.

With composting toilets it's important to use an easily biodegradable paper, which is perhaps the hardest thing to adjust to. No Charmin Ultra Soft in this application.
I used to get a catalog for these composting toilets but they are not permitted in the area that I wanted to build on.
Ed Begley, Jr. - Beverly Hills... things are changing. And sometimes you have to push.

In the area I'm building they have seen the light, because composting toilets are so much better than cesspools, which used to be the default if a septic system wasn't feasible.
Terrific article, David. I love the detail. It makes me want to build one of these houses to live in. Thank you for this series.
Thanks for this series. I always thought I would end up a destitute old woman living in my daughter's basement, but hmmmm....your off-the-grid low cost housing designs are looking very attractive.

All kidding aside, you are doing valuable work, and I honor you for it. Thanks again.
Altaira, thank you. A friend sent me a recent AARP article about a similar housing concept for seniors, a modular unit to place in their child's back yard. With a different design target, only the general concept is the same, so it's purpose built, accommodates medical equipment, and sells for $65,000.

I think this plan, which I'm targeting at under $15,000 completely equipped and furnished (not counting labor, which can be owner supplied) could be a housing solution for many low income populations, including seniors.

I've investigated many "alternative" designs, including yurts and domes, but the great strength of the container, plus the fact that it can provide instant shelter at low cost are compelling characteristics. And reusing what is currently a "disposal problem" is the cherry on the hot fudge sundae for me.
This is amazing, you truly are brilliant. Now I will have something to talk about on girls night out.
Thanks Mark. The numbers are actually quite good. These containers are built to stack up to 8 high, so they are inherently stronger than wood frame structures or manufactured housing. And at $25 sq ft for a basic structure dropped on a lot ready to go, it's 1/3 the cost of the same thing purpose built (current Big Island cost).

And part of the game for me is to see if I can utilize green technologies like rainwater catchment and solar power to save money on the entire project, rather than paying the large premium that people are used to paying for those technologies now.

I'll talk about the solar aspects next.
You're not crazy, no. But a little word of caution... what makes compost piles work is aerobic bacterial digestion of organic matter, and the clay base of most kitty litters is non-organic and indigestible. So be careful that you don't overload the pile with too much litter. The pile should be hot when it's working. Turn up a forkful when it is cold out and it should be steaming inside.
Yes, if someone did that, it would make a mess. But fortunately, it would be easy to clean up. One of the reasons I selected the Nature's Head is that it has inexpensive spare waste containers available, with lids, and they are easily exchanged. Then the whole area is easily hosed down.

The idea of being able to hose down the entire bathroom with the shower head is one I borrowed from Buckminster Fuller's brilliant Dymaxion Bathroom design from 1936.

My ex was so entranced by the idea she suggested that the rest of the house be done the same way, with a big drain in the middle of the floor, and a firehose in each room to do the housecleaning with. Fwooosh, fwoosh, done!