The Owner Built Home and Homestead: Human Composting Privy

Architects Journal, 1965

In this multi-volumed and progressively-written book I have
attempted to present the results of my research precisely
along the lines of the functional revolt–as applied
to the low-cost or owner-built home. In the course of my
thinking and writing, I have been guided somewhat by
readers’ comments and questions on previous chapters. These
have constituted a kind of feed-back on my researches. What
were the readers’ particular problem areas? Such
considerations should assist in the formation of new
chapters or supplements–even new volumes or books.

The present chapter is a definite response to readers’
comments. More readers picked up an offhand mention of the
squat-toilet (p. 38) than any other item in Volume III. So
the squat-toilet idea will be discussed here. And it will
be discussed in its proper context as a feature of the
large problem of bathroom waste disposal. A proper
toilet suggests a proper disposal system and this further
suggests a proper structure to accommodate the necessary
facilities.

And by “proper” I refer, as usual, to Ralph Borsodi’s
criteria: Is it healthful? Is it economical? Is it pleasing
to behold? One need not be reminded that modern bathroom
systems are ugly, expensive and unhealthful. If you wish to
know how much your conventional bathroom plumbing and
drainage system costs, count the number of fixtures in the
house, including lavatories, water closets, bathtub, water
heater. This total multiplied by $400 gives a close
estimate of plumbing costs. Add to this the room area
multiplied by $10 and you have a surprising total of about
$2500 for an average-size bathroom and drainage facility.

Finally, the “healthful” aspects must be considered. It can
be factually stated that the conventional water toilet is
not healthful. The high sitting position is artificial and
unhygienic. Nor is it healthful to pollute bodies of water
with water-borne sewage. Each year 4.5 million tons of
sewage sludge is dumped into the oceans from North America.
This represents 4.5 million tons of nitrite contaminant and
it also represents 4.5 million tons of potentially valuable
fertilizer not returned to the land. The experts
are in unanimous agreement on the subject of toilet height
(as quoted from Kira’s book):

The ideal posture for defecation is the squatting position,
with the thighs flexed upon the abdomen. In this way the
capacity of the abdominal cavity is greatly diminished and
intra-abdominal pressure increased, thus encouraging the
expulsion of the fecal mass. The modern toilet seat in many
instances is too high even for some adults. The practice of
having young children use adult toilet seats is to be
deplored. Beckus, Gastro-Enterology, p .
511.

Man’s natural attitude during defecation is a squatting
one, such as may be observed amongst field workers or
natives. Fashion, in the guise of the ordinary water
closet, forbids the emptying of the lower bowel in the way
Nature intended . . . It is no overstatement to say that
the adoption of the squatting attitude would in itself help
in no small measure to remedy the greatest physical vice of
the white race, the constipation that has become a
contentment. Hornibrook, The Culture of the
Abdomen, p . 75.

It should be mentioned in this connection that a very
common cause for unsatisfactory results . . . is improper
height of the toilet seat. It is usually too high. An ideal
seat would place the body in the position naturally assumed
by man in primitive conditions. The seat should be low
enough to bring the knees above the seat level. Williams,
Personal Hygiene Applied, p. 374.

The high toilet seat may prevent complete evacuation. The
natural position for defecation, assumed by primitive
races, is the squatting position . . . When the thighs are
pressed against the abdominal muscles in this position; the
pressure within the abdomen is greatly increased, so that
the rectum is more completely emptied. Our toilets are not
constructed according to physiological requirements. Aaron,
Our Common Ailment , p.66.

The Thailand government has had a long-established program
of improving rural latrines at Chiengnai. Perhaps the most
recent achievement in this area has been the development of
a water-seal squat-type (squatting plate) toilet bowl that
any farmer can build for less than a dollar’s worth of
material. The Thailand Ministry of Health sells a
2-component cast aluminum master mold from which countless
numbers of units can be built. I secured a couple of these
Chiengnai molds for our owes experimentation–and to
loan out to people interested in building their own toilet
bowls.

The finished toilet bowl is quite satisfactory. It takes
about one quart of water to flush the unit–as opposed
to 4 gallons for the conventional water closets. The bowl
can be maintained clean and sanitary without difficulty.
And most important of all, the use of this bowl
necessitates a natural evacuation posture.

The use of a squatting plate suggests a re-evaluation and
redesign of the complete bathroom facility. The room I
propose is in effect a four-foot diameter shower stall. A
single flexible water inlet–of the type commonly used
in Denmark–supplies showering, lavatory washing and
bowl flushing. A single drain disposes of all wash and
flushing water through the bowl trap. (Ideally, a solar
water heater and storage facility directly overhead
supplies consistent warm water needs.) Directly below the
squatting plate an excreta-disposal compartment is
provided.

There are two basic methods of excreta disposal: The
compost privy and the septic tank. The first process is
aerobic and requires oxygen in its fermentation
process of decomposition. The second is anaerobic
and consists of a putrefactive breakdown–in places
where oxygen does not have access. We must choose between
fermentation and putrefaction in our attempt (1) to reclaim
the nutrient and fertilizer value of waste, and (2) to
dispose of excreta waste in a sanitary manner.

World Health Organization publications present a compelling
argument against handling excreta in an anaerobic (sewage
and septic tank) manner. As a result of not having oxygen
in a putrifactive action, no heat build-up occurs and
therefore certain pathogens and parasites are not fully
destroyed. It has been found that contaminated material in
liquid suspension (anaerobic digestion) can remain viable
for as long as six months. For one thing, there are far
more species of bacteria involved in aerobic decomposition
than in anaerobic putrification.

Other problems are associated with the disposal of
water-borne waste. Sewage necessarily containing large
quantities of water (necessary for the transport of the
excreta) is difficult to treat. Water does have a certain
ability for self-purification. But this requires oxidation
and usually the volume of water is too small in proportion
to sewage to supply the required quantity of oxygen.
Consequently the receiving water becomes foul and normal
fauna (especially fish which require oxygen to live) are
destroyed. The receiving water also becomes contaminated
with pathogenic bacteria, protozoa, and with the eggs and
larvae of harmful helminths (liver flukes).

Our society not only legalizes pollutive unsanitary
disposal methods, it also outlaws an improved
nutrition–an essential factor in prevention of
disease–which is obtained when excreta wastes are
returned to agricultural lands as plant nutrients.

The only really practical way to reclaim these wastes is
through aerobic composting. Pathogenic bacteria and worm
eggs can survive no longer than 30 minutes to 1 hour in a
compost situation. Compost temperatures rise to 160 degrees
F. High temperatures, however, are only partly responsible
for this bacteria destruction; competing bacterial flora
and predatory protozoa contribute as well. Aerobic
composting is achieved by a wide succession of bacterial
and fungal populations–each suited to its own
environment and its own relative duration: The activities
of one group compliment the other.

Humus is the end-product of properly composted organic
materials. Humus contributes to increased nitrogen-fixation
in the soil from nitrogen in the air. Also, as the gradual
decomposition of insoluble organic matter takes place,
nitrogen is liberated (as ammonia) and then oxidized to
nitrates. Plants can utilize this nitrogen only in the form
of nitrates. So when raw (not composted) wastes are spread
on the land–as is commonly done in the
Orient–nitrogen evaporates into the air instead of
being used by plants.

The primary key to good compost-building is to establish
correct proportioning and blending of the raw materials. In
essence the problem is one of determining carbon and
nitrogen ratios (C/N), along with the correct amount of
moisture and aeration. Cellulose organic matter like straw
or sawdust is rich in carbon, and excreta are rich in
nitrogen. It has been found desirable to keep the C/N ratio
above 30 to 1 when excreta is used; excreta should equal
10% to 25% of the total weight. Urine contains considerable
larger amounts of nitrogen than do feces. Raw garbage has a
C/N ratio of 25 to 1; sawdust, 511 to 1; farmyard manure;
14 to 1.

Aeration helps maintain the required high temperatures in
an aerobic composting condition. Turning the compost pile
at frequent intervals has been a traditional method of
achieving aeration. Yet, turning adversely effects nitrogen
conservation. Ammonia readily escapes to the atmosphere
when the material is disturbed and exposed.

As one becomes more familiar with the whole process of
aerobic composting, the design of an appropriate facility
falls into place. The facility design can be likened to
that of a furnace: Material (fuel) is placed in a
combustion chamber; a vent stack (chimney) is provided to
carry off gases that are produced from the decomposition
(methane, carbon-dioxide, ammonia); and, finally, a storage
compartment must be supplied for the end product (humus, or
ash, in the case of a furnace).

The size of the facility depends, of course, upon the
number of people using it. About 2 pounds of excreta per
person per day, or 1 1/2 cubic feet per person per year, is
used as a design figure.

If the initial C/N ratio is 30 to 1, it takes about 10 days
composting time; a 78 to 1 ratio takes 20 days. Using the 1
to 5 volume ratio of excreta to refuse, and figuring that a
family of five will produce about 1 cubic yard of partly
digested excreta in four years, a compartment size of 1
cubic yard would fill in about 9 months. It must be
remembered, however, that decomposition into gases and
soluble materials reduces volume and mass as much as 80%.

The Indian Council of Agricultural Research at Bangalore
developed extensive composting programs based on the
compost privy principle.

They built an experimental “double vault” latrine. During
the time that one compartment was being used, compost
material in the adjacent compartment was ripening. A period
of 6 months lapsed between clean-outs, This two-compartment
system appears to be superior to others. However by
incorporating a simple damper mechanism, only one squatting
plate need be provided.

Rikard Lindstrom of Tyreso, Sweden, has patented a simple
aerobic composting chamber. Its salient feature consists of
a sloping (16-degree) bottom to the tank, which provides
for a continual movement of the decomposed refuse to a
storage chamber as additional wastes are added to the other
compartment. The chamber bottom should contain a thick lays
(12-inches) of straw or sawdust so that urine will be
absorbed and reclaimed. This porous layer of cellulose also
provides aeration to the central section of the pile.
Lindstrom used a system of inverted U-shaped conduits and
ventilation holes to provide adequate aeration. Air
circulation is also accelerated through solar-heated flue
conversion.

In Japan, where excreta is traditionally used as a
fertilizer, powdered soybean is often added. Enzymes in the
soybean speed up the breakdown of organic solids. Kazuyoshi
Yamaji of Tokyo holds a U.S. patent on a “powdered
deodorizer of the acceleration of ripening of organic
fertilization fertilizers.” A dried and powdered cereal
containing a large quantity of enzyme is first mixed with
rice-bran, barley-bran, or wheat-bran. Water is added and
it is heaped for fermentation. It is then dried and
powdered and mixed with tricalcium phosphate and the powder
of germinated seeds of cereal such as barley, wheat, bean,
etc. which contains a large quantity of enzyme. Only a
small quantity of the finished product need be sprinkled on
the excreta.

Bio-Dynamic gardeners use a special
preparation–inocula–in making compost humus.
The formula is based on the researches of the late Dr.
Rudolf Steiner. One of these exotic preparations (502) is
made from yarrow blossoms, fermented together with deer
bladders over a period of 6 months in earth during the
winter.

Using enzymes, hormones, or biocatalysts in the
decomposition of organic material and for nitrogen fixation
may prove to be an interesting sideline, but none of these
inocula are really necessary to a properly balanced compost
environment. Organic material contains all the growth
factors and vitamins necessary for normal development.
These growth factors are produced by micro-organisms in
sufficient quantities in a mixed microbial population to
meet normal growth requirements.

From the point of view of cost, health, and good design, I
recommend the cylinder-shaped structure. The 4-foot
diameter structure contains, in its series of levels:
Effluent drainage pit, compost chamber, bathroom facility,
solar water heater. A very simple slip-form jig can be
employed to build the solid concrete walls. The complete
unit is available from me for loan to interested people.
Floor and roof are cast-in-place concrete. Ideally the unit
would be built on a hillside to provide best access to the
compost compartment. It can be built as a detached
structure or connected to hall, breezeway or directly to
sleeping unit. The accompanying drawings and photos best
illustrate the structure and techniques of construction.

A widespread use of the compost privy is not to be
expected. There are many social, legal, and technical
difficulties associated with adopting this new functional
mode of handling human excreta. For clarification on
specific aspects, ask your friendly Building Inspector. In
my judgement the long term personal rewards and benefits to
the environment warrant whatever manner of subterfuge
deemed necessary to build the compost privy. No County
Building Department should have the power to prevent my
squatting to relieve myself, nor should it prevent compost
activities limited to my own garden.

Bibliography (Books listed in order of
importance)
An Agricultural Testament; Albert Howard

Excreta Disposal; World Health Organization
Composting; World Health Organization
The Bathroom; Alexander Kira
Fertility From Town Wastes; Wylie

MORE KEN KERN (THIS TIME “OWNER-BUILT HOMESTEAD”) COMING IN MOTHER EARTH NEWS NO. 7.