What's your take on this method? Rainwater, grey water, humanure

I've spent much of the past weeks reading through this website which I found to be very information-dense, a little repetitive, and a bit verbose, but quite interesting.

Some things kind of rubbed me the wrong way, and I wanted to get some other perspectives on them.

Here's a quick(er than reading the entire website) summary:


I'd like to first summarize what I understand the position of the author of the website to be, then discuss my own current perspectives.

Essentially, the solutions offered by mainstream ecological sanitation are ineffective because they are starting with the wrong premise and do not take a holistic view.

To that end, they developed their own set of guiding principles:
Principle n° 1 : Collect and treat greywater and black water separately
Principle n° 2 : Never release black water into the environment
Principle n° 3 : Restore the humus content and biodiversity of soils
Principle n° 4 : Reuse greywater for irrigation and groundwater recharge
Principle n° 5 : Avoid the discharge of wastewater into surface waters
Principle n° 6 : Adapt water quality to its end-uses

Just as most advanced societies now recognize the wisdom of source-separating municipal solid wastes into organic waste, various reusable/recyclable wastes (glass, paper, packaging), and other wastes like lightbulbs, batteries, aerosol cans, diapers, etc. the author advocates source-separating out wastewater, a position not held by many leading authorities. Rather, most municipal water treatment subscribes to the school of thought "The solution to the pollution is dilution" and they combine all forms of wastewater into one system, which then has to (at great cost) remove harmful chemicals and bacteria before releasing the water into the nearest water course, turning our rivers and oceans into a giant toilet/landfill.

Principles 1 and 2 are about separating household grey water and black water.  Best case, don't create black water in the first place, but use a dry toilet, and compost what is collected.  But if you can't or won't abandon a flush toilet, use a low flow flush toilet and channel those pipes to a designated black water treatment facility (where they will compost what is collected at a much larger scale).  This allows city dwellers who don't have capacity to compost that much humanure themselves to participate without changing their lifestyles. They likely would not even be aware of any differences.

Principle 3 deals with why composting humanure is essential, because other humanure disposal methods are far removed from the idea of "highest, best use" of the resource.  Depleting the soil (life, quality, and volume) is a slow suicide for the planet and everything on it. Restoring the soil is essential.  Throwing away the building blocks of the soil by actively removing or destroying humanure (modern sanitation practice, incineration/biochar, biogas, etc.) is foolish and causes more harm than good in the long run.  (He gets very scientific with his explanations of changing the molecular makeup, ionization, methanization and so on, and my eyes sort of glaze over.) Composting of humanure ONLY happens when immediately combined with plant/based, carbon material.

Principle 4 is about using grey water (NOT combined with black water and therefore basically free of pathogens and excessive nitrogen and phosphorus). It can be filtered and treated, mostly with sunlight and time, in comparison with processes like phytoremediation.  It can then be used to water plants, infiltrated into the ground, and will recharge aquifers and underground water sources.

The 5th principle is about isolating all sources of wastewater from natural water systems.  The idea that we should put anything into the ocean as fast as we can is absurd.  Humanure makes compost, grey water gets treated and added back to GROUNDwater. Rivers and oceans are far less equipped to deal with our wastewater than the soil life.

The 6th principle is that all household water does not have to have the purity of drinking water.  Humans only need 3-5 liters of water per person per day. We don't need to shower in, wash laundry with, or defecate into drinking water.  If households collect rainwater as recommended, far less infrastructure/costs are involved to use rainwater for household use, and whatever is needed for drinking can be taken from the city water supply, or with a small amount of additional filtration. from the collected rainwater as well.


TL;DR: If households would collect rainwater for nearly every use, and separate grey water from black water/humanure, and use both to create valuable resources rather than treat them as waste, we could have healthier, more vibrant soil and aquatic ecosystems, as well as a sustainable, autonomous water supply.


If anyone has read through the website or is familiar with these concepts, please let me know if I've understood everything correctly.

Now here are some small details I got hung up on, perhaps mostly influenced by Paul's podcasts about these topics:

1.  He doesn't advocate urine separation.  He makes a strawman argument saying that those who advocate separating are only concerned with how often they have to empty the collection bucket.  I'm not concerned with that, but I believe urine separation is better, in the same way that separating grey water from black water is better.  They are different resources, have different qualities and attributes, and a one-size-fits-all solution doesn't make sense.  He further states that combining urine and humanure REDUCES odors, which is the opposite of what I've heard elsewhere.  He mentions draining urine away, so it's not "poop Kool-aid" as Paul likes to say, but where does the urine in his system actually go?

2. He talks about how separated urine needs to be highly diluted before being used on plants so isn't "really" all that water-conservation-friendly. He talks about 200 kg of nitrogen/hectare/year being the limit, and that's a bit beyond me, technically. I believe urine doesn't "always" need to be diluted. It is my further understanding that urine CAN go into a grey water system, so there's your dilution without wasting additional water.

3. Biogas doesn't seem to be a good method of dealing with humanure.  Many posts here on permies seem to concur, that it takes a LOT of humanure to create biogas.  Also, if humanure can be better used to create soil, fine.  But then the question arises, what IS an appropriate feedstock for biogas?  (The author seems to say that biogas production is generally a bad idea, but perhaps he meant only in reference to humanure?) I've heard that you can feed a biogas digester with grey water.  Wouldn't this be essentially the same as what he means by an "anaerobic batch reactor" with the added benefit of harvesting biogas? isn't a biogas digester basically the same as a septic tank with benefits? With or without the addition of urine, this seems like a good use of resources.

I'm sure there are other things, but I'm out of time and can't think of anything specific off-hand. I'd like to suggest these perspectives to the author, but would find it incredibly presumptuous to write to him and say "here's what I find wrong with the concept you've spent decades researching and creating." No matter how I might approach it, it just feels rude.

Perhaps I'm missing something. What are your thoughts?

There are a few municipal systems that process humanure into fertilizer (google Milorganite), however even treating it to kill pathogens, etc. doesn't remove metals and some pharmaceuticals. Potential problems with using poop as fertilizer

As for his contention that we are dangerously depleting soil by not returning the humanure, I don't believe humanure is a large enough source of nutrients to make any measurable difference.

I believe this is one of those issues that will solve itself over time.
While it may be fairly simple to separate black and grey water streams on an individual house, trying to renovate +1 billion homes is not so simple.  Even for many existing homes it's not simple.  My house is built on a 'slab' so accessing the drain pipes requires either cutting through the slab, or tunneling under it.  I was able to access the drains for the kitchen sink and laundry by running pipes out through the walls, but accessing the shower in the master bathroom required tunneling under the slab about 4 feet.  I didn't bother with trying to get to the tub(rarely use it) or bathroom sinks (insignificant amount of water).

However, some places are already working on the issue.  I live in Arizona and a few years back they made it mandatory on all new housing that the grey water and black water plumbing are separate until they get outside the house, then they can be combined.  This makes it easier to convert the home in the future.  There are a few other areas that have similar rules.
A major problem with separating grey and black water, especially when combined with low flush toilets, is that you can end up with insufficient fluids to flush the solids through the pipes.  There are ways to solve this, but they require completely re-engineering or replacing the existing sewer systems.

Composting toilets sound great...to people who have never used them.  The simple ones are often smelly, require a fair amount of work and tend to accumulate these tiny annoying flies.  The more complicated systems, are...complicated, expensive, large (often having a large composter in the basement, etc.), and still require a fair amount of maintenance.

Biogas digesters don't really 'solve' anything.  Humanure does not produce significant amounts of biogas and even if the digester kills off pathogens, you still potentially have the issues of metals, pharmaceuticals, etc.

Some of our urine goes into our grey water, but it does require significant dilution.  It's not just the nitrogen that is a concern, urine is also high in sodium (salts) and this must be diluted or it will build up in the soil.  The minimum recommended dilution ratio is 8:1 with 15:1 or higher being better.  The average person produces 1-2 liters (~1/2 gallon) of urine per day.  So as long as you produce about 30 liters (8 gallons) of grey water per person per day, then it makes sense to include the urine in your grey water.

Thank you, those are some very informative posts and links. This is a discussion that needs to happen -- there is no single solution that will work in all different situations. (For example, climate, and population density)

Peter VanDerWal wrote:
As for his contention that we are dangerously depleting soil by not returning the humanure, I don't believe humanure is a large enough source of nutrients to make any measurable difference.

The nutrients we produce in our urine and feces are largely equal to the nutrients we eat, and the nutrients required to add to land in order to produce the food we harvest off it are largely equal to the nutrients harvested. Another lovely cycle, like the water cycle. Nitrogen is the one nutrient that goes up into the atmosphere and comes down from it easily; the others are largely earthbound. So it seems to me that humanure can be a good source of nutrients.

Municipal sludge is a whole different story though, what with all the microplastics, medicines, flushed toxics, and who knows what else. Home scale humanure is more likely to be managed safely for various reasons.

Rebecca Norman wrote:The nutrients we produce in our urine and feces are largely equal to the nutrients we eat, and the nutrients required to add to land in order to produce the food we harvest off it are largely equal to the nutrients harvested. Another lovely cycle, like the water cycle.

So much wisdom in that statement!

Rebecca Norman wrote:The nutrients we produce in our urine and feces are largely equal to the nutrients we eat,

The nutrients eaten by humans are relatively tiny on a global scale and many of the "nutrients" we eat are not expelled in urine of feces.  Most of the organic compounds(carbohydrates, protein, fat) we eat does not end up in our waste.

Incinerating human waste does NOT destroy the chemical elements (nitrogen, phosphorous, potassium, etc. ), minerals or even many of the compounds.  It mostly breaks down the organic compounds.

The overwhelming majority(75%) of the mass in human feces is water.
Of the remaining 25%, about 1/3 is bacteria, 15-20% is inorganic compounds (phosphates mostly) and about 1/3 is fat and protein.   So perhaps 2-3 grams of fat and protein per person per day.

Peter VanDerWal wrote:There are a few municipal systems that process humanure into fertilizer (google Milorganite), however even treating it to kill pathogens, etc. doesn't remove metals and some pharmaceuticals. Potential problems with using poop as fertilizer

The author behind the Eautarcie website would agree with your article and also does not suggest using poop as fertilizer. Rather, he composts it. Subtle but significant difference.

As for his contention that we are dangerously depleting soil by not returning the humanure, I don't believe humanure is a large enough source of nutrients to make any measurable difference.

My sense is that he's not looking at the chemical properties so much as the physical ones. The volume of soil produced and the biodiversity it enables. Looking to BUILD organic compounds, not break them down.

Composting toilets sound great...to people who have never used them.  The simple ones are often smelly, require a fair amount of work and tend to accumulate these tiny annoying flies.  The more complicated systems, are...complicated, expensive, large (often having a large composter in the basement, etc.), and still require a fair amount of maintenance.

My experience with my own toilet blatantly contradicts every single point you make here. No smell, no flies, little effort, small, cheap DIY, nothing complicated at all, low maintenance. Maybe you had some bad experiences, or maybe it's conjecture. Either way, I suppose "don't throw the baby out with the bath water" is a good approach.

Chad Sentman wrote:

As for his contention that we are dangerously depleting soil by not returning the humanure, I don't believe humanure is a large enough source of nutrients to make any measurable difference.

My sense is that he's not looking at the chemical properties so much as the physical ones. The volume of soil produced and the biodiversity it enables. Looking to BUILD organic compounds, not break them down.

Composting toilets sound great...to people who have never used them.  The simple ones are often smelly, require a fair amount of work and tend to accumulate these tiny annoying flies.  The more complicated systems, are...complicated, expensive, large (often having a large composter in the basement, etc.), and still require a fair amount of maintenance.

My experience with my own toilet blatantly contradicts every single point you make here. No smell, no flies, little effort, small, cheap DIY, nothing complicated at all, low maintenance. Maybe you had some bad experiences, or maybe it's conjecture. Either way, I suppose "don't throw the baby out with the bath water" is a good approach.

I still believe he is vastly overstating the issue.  On a global scale, human consumption is tiny.  Add to that the vast majority (probably 75%+) of humans live in areas without sewer/septic systems, those people are already composting/burying their waste.
Of the remaining ~25% of a tiny amount (globally), most live in cities, etc. where individual composting is not practical.  The large scale composting he talks about would require expensive changes to the existing infrastructure.  The ecological impact of building new infrastructure would probably outweigh the tiny benefit.
When it comes time to build new facilities, or replace old ones, then it might make sense.   But replacing working facilities solely for the sake of getting the compost, does not make sense at this time.

My comments about composting toilets was from my experience of living with one for 6 months.  Perhaps you are lucky, but the issues with smell and flies are common complaints, even here on Permies.
https://permies.com/t/59681/double-chamber-composting-toilet
https://permies.com/t/56869/Wood-chip-bucket-toilet
https://permies.com/t/50141/compost-technology-add-living-spaces

I'm not saying they smell bad all the time,  but when the wind was just right even powered ventilation didn't always work.
While the maintenance, etc. are not huge, they require significantly more work than simply pushing a lever.

They make more complicated composting systems, that solve almost all of these issues.  They use extremely low flush toilets (like RV toilets) and drop down into a large semi-automated system that only requires occasionally removing the partially composted waste and burying it for 6 months or so to finish, but these are VERY expensive.

Anyway, the point is that it's not a simple solution.  As the author points out, individual composting does not work in urban environments, and even in rural areas the majority of people aren't willing to put up with the additional hassles, potential problems of composting for the minimal benefits.  This is especially true if they already have a working sewer/septic system.

Something else to consider.  Not everyone has ready access to saw dust, wood chips, etc.  Where I lived before when using the composting toilet, and where I live now, the environmental impact of hauling in saw dust/wood chips probably outweighs the positive impact of composting humanure.  This would become an even larger issue if large number of people were composting their waste (where do you get all the saw dust)

Some people talk about the large amounts of compost they produce from humanure, without really considering that the majority of the finished volume comes from the sawdust/wood chips/etc.

As for urine; as long as you have enough land, and enough water to dilute it adequately, then that makes sense to use it.  
Note: it requires approx 1/16 acre per person to avoid issues with excess nitrogen and salt build up.  So again it doesn't make sense in urban or even most suburban areas.

(edited)  Chad, I agree...  I think biogas is high in methane, and methane has relatively high energy content.  So the feed material has to have significant chemical-energy content in order to be a source of energy.  As I understand it, usually this means a material that contains a significant amount of "woody" ligno-cellulose like wood or grass.   Often this comes from the grass and hay eating animals.  Cow manure contains 1/3 of the original chemical energy in the grass, and horse manure contains 1/2.  Furthermore, in manure, that grass has been partially digested and is full of the microbial bacterial cultures that apparently can thrive in that environment, even anaerobically, and produce the enzymes needed to breakdown that difficult to digest, yet energy-rich material, all of which is needed to produce methane biogas, as far as I know.

So, AFAIK, humans and or microbiome in general don't metabolize cellulose, and we usually say that the "fiber" passes right through us.  I'd guess humanure could probably be thrown into a digester, but it probably wouldn't add much to the biogas production.  One might as well just throw the fiber in the digester without bothering to pass it through your gut undigested.  

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My general thoughts on this topic and my opinion is we ought to find a way to sterilize the dejecta on something close to a per-flush basis (whether it's done in the toilet or a tank or a pipe leading to the tank).  If this *isn't* done, then someone will always be able to claim that what you're doing is "unsanitary" (whether rightly or wrongly, in some sense it doesn't matter because they can still make the claim).  However, if the dejecta *is* sterilized on a per-flush basis then it seems there is far less justification to claim a public risk regarding what you do with the sterile "dirt" that results.  Basically it can probably go right in your personal compost pile at that point because it's safer than ordinary dirt.  

Unfortunately, how to do that seems a bit challenging as a technical problem.  This probably would require some kind of thermal energy source, almost any kind, to "cook" the dejecta past some minimum temperature profile.   I suppose that such a system could be made in a water-based version, or a dry version, particularly if the dry version used non-stick surfaces and/or some sort of disposable, compostable "liner" material to make it easier to clean.  The heat source might also be combined with de-odorizing if the surrounding air is "flamed" to burn off any odors.  I think this method would tend maximize the agricultural value while minimizing the health-safety issues.  By not incinerating the dejecta, the plant nutrient value isn't lost.  

Unfortunately this would require some investment and some energy use, however, it still may be lower in these regards than other options.  The value of having a safe source of compost of known origin could help offset the cost of such a system.  

This is just a theoretical concept though.

I think people should keep their own compost pile, and grow flowers in the resulting compost.  This avoids the issue of cross-contaminating your waste-stream with your neighbors.  A flower might make a good logo to represent that the system is clean and green.  

Chad Sentman wrote:Principle n° 2 : Never release black water into the environment

While I agree with this principle as it applies to untreated black water... we treat all of our household raw sewage with aeration exactly like municipal sewage treatment plants do. After being thoroughly aerated, the black water is clarified by settling and then flows through a filter into a sump where it gets pumped up to a storage tank. Once black water has been aerated it does not turn foul again even with prolonged storage. We use the reclaimed processed black water to irrigate our fruit trees and grape vines. All of the water we pay to use once... gets used twice.

Urine=Medicine metabolites so I vote that it is not so easy as grey water and might be

Graywater =In a city the avg apartment building or PUD could easily re-use grey water onsite without alot of effort or much work effort from/skill/eco-friendly mindset vs say telling everyone in a city to use a composting toilet.

My 2 cents:
greywater is NOT sterile,
urine is sometimes sterile, usually pathogen free, not chemical free.

Nutrient cycling through humans is not insignificant or trivial,  there are a lot of us.

Humans are roughly 1/4 of mammalian biomass on the planet,  our livestock is roughly half
https://www.google.com/amp/s/www.researchgate.net/figure/Global-change-in-the-collective-mass-for-wild-mammals-humans-cattle-and-all-livestock_fig7_275657970/amp

https://m.phys.org/news/2018-06-scientists-history-environmental-collapse.html

Though bugs and sealife out weigh us by several orders of magnitude
And microbial life is vastly more
https://www.vox.com/science-and-health/2018/5/29/17386112/all-life-on-earth-chart-weight-plants-animals-pnas

The problem of human waste has two branches, urban,and rural.  

USA is roughly 86% urban/suburban vs  14% Rural
http://www.pewsocialtrends.org/2018/05/22/demographic-and-economic-trends-in-urban-suburban-and-rural-communities/

World is just over half urban with africa and latin america below half, and europe, North America and East Asia above.
https://ourworldindata.org/urbanization

I loved the humanure handbook, and have used many composting toilets,  all of which had strong odor and insect issues.  

my recomendations:  urban areas have the wealth and scale to process black and grey water into a safe fertilizer if they choose.  Right now we are wasting that resource ,and contaminating our surface waters.  Close the cycle.

Rural areas could compost blackwater and irrigate with grey water more cheaply and with less expense and ground water contamination than a septic system.  

We're going to be building/repairing lot of infrastructure anyway, with population growth,  climate increased natural disasters (floods, wildfire, sealevel).  Might as well build the new stuff to recycle our wastes and,save our waters.

Also, incinolets give off a horrible odor.  And very energy intensive.  irradiation of waste is only a temporary sterilant because the nutrient rich manuer are easily recolonized.

Ok,  i guess thats 3 cents

Joseph Michael Anderson wrote:
my recomendations:  urban areas have the wealth and scale to process black and grey water into a safe fertilizer if they choose.  Right now we are wasting that resource ,and contaminating our surface waters.  Close the cycle.

Rural areas could compost blackwater and irrigate with grey water more cheaply and with less expense and ground water contamination than a septic system.

That's what we do to close our own cycle.
Smelly black water composted by aeration transforms into odorless pond water suitable for irrigation and fish ponds. The sludge is harvested and used as valuable fertilizer to replenish the soil. Both liquid and solid, all of our sewage gets reused over and over in a sustainable cycle.