re: d.i.y. composting toilet
8 mar 1998
j garrett wrote:
>...i would like to fit a composting toilet in the house to 1 conserve
>water. 2 save money on building a septic system ( i am using the grey
>water for irrigation.). 3 use the residue on the vegies... any info,
>plans or help will be most appreciated..
"the humanure handbook," by joseph c. jenkins (third printing, chelsea
green, 1994, isbn 0-9644258-4-x, "198 pages, indexed, with glossary,
appendices, 63 tables and figures, 9 sidebars, 19 photographs, and a
few bad jokes," $19 us) describes how to build a "sawdust toilet" with
a 5 gallon plastic bucket under a 3/4" plywood box with a standard
toilet seat mounted on top of the hinged plywood lid. the top of the
bucket is flush with the bottom of the toilet seat, so there isn't much
odor when the seat is folded down.
figure 7.1 on page 154 describes the process:
1. go to donut shop and buy a used 5 gallon plastic bucket
(buy 2, use one for cover material.)
2. set bucket on floor indoors in pleasant, ventilated, sunny,
private space. build toilet seat around it. use conventional toilet seat.
3. find a souce of sawdust and keep a supply handy to the toilet as cover
material. one adult will fill a five gallon bucket in about 6 days.
4. use toilet. (cover deposits.)
5. deposit humanure on [outdoor, thermophilic] compost pile. cover
adequately with straw, hay or weeds. scrub bucket [he suggests having a
rainwater supply handy] and pour water on pile. return clean bucket
to toilet. dust inside of bucket with sawdust.
6. season compost. use double-chambered compost bin. when one side is full
(should take a year), leave it to season and start filling the other side.
put kitchen garbage and garden refuse in same compost bin. use compost
thermometer to monitor compost temperature.
7. apply to soil. when second bin is nearly full (a year later) empty
first bin onto garden or field. when second bin is full, leave it to
age and begin filling first bin again.
8. grow your own food. notice that you have created no waste, pollution
or health hazard, and your human nutrient cycle has been kept intact!
9. answer nature's call...
the "sawdust toilet vital statistics" sidebar says:
100 pounds of human body weight will fill approx. 3 gallons (0.4
cubic feet, or 693 cubic inches or approx. 11 liters) in a sawdust
toilet per week -- this volume includes the sawdust cover material.
100 pounds of human body weight will also require approximately 3
gallons of semi-dry, deciduous, rotting sawdust per week for use as
a cover material in a toilet. this amounts to a requirement of
approximately 20 cubic feet of sawdust cover material per 100 pounds
of body weight per year for the proper functioning of a sawdust toilet.
human excrement tends to add weight rather than volume to a sawdust
toilet, as it is primarily liquid and fills the air spaces in the
sawdust. therefore, for every gallon of sawdust-covered excrement
collected in a sawdust toilet, nearly a gallon of cover material
will have to be used.
the book has lots of detailed technical information, including tables
of how long it takes to kill various pathogens at various temperatures.
one glossary entry:
fecophobia: fear of fecal material, especially in regard to
the use of human fecal material for agricultural purposes.