Build your own Composting Toilet and

save water.
DISCLAIMER : - The drawings, proceedures and words are for information only. No
claims are expressed or implied as to the safety, usefulness, or accuracy of this
information. I will not accept any liability for any damages caused to people or property
from the using of this information or from any associated links. Your actions are your
responsibility - VERIFY and CHECK information out before proceeding, and don't attempt
anything without the required skills, if you cannot agree to this, leave this page now . . . . .
. . Chris.

This is a project I have yet to finish, I have to provide proper toiletries for the family ( and any visitors ) at
our bush block. There are many designs about and all are pretty similar, achieving the same thing in
slightly different ways , but I like this because it is simple and straight forward. It is similar to "Nature
Loo" , (EMAIL- natloo@ozemail.com.au.) Their design however uses a specially designed chamber
which optimises air flow through the compost heap and has better dimensions for the task. The version
here is a variation of a couple of designs, using cheaply available bits, and using the building codes
recommended for vents, trenches etc.

Materials needed are: 2 (or more) black "pickle barrels" , these can be picked up cheaply from 20-50
dollars. Their about 1 metre high and a bit over 500mm wide, and very useful to have for all sorts of jobs
( sorry) around the property .Unfortunately their value has been recognized by some and the price
adjusted ! A few metres of 100mm storm water pipe for the vent pipe, two 100mm " T" sections, 2,
100mm end caps some 50-80 mm flexible hose, 10 metres of uv stabilised 20-30 mm hose , a circular
piece of gauze ~ 3/32 pitch and about 400mm dia, (cut later to size ) , about 1 square metre of floor reo ,
A few 12v computer fans, and a toilet pedestal, with an air tight seat . This has to be a "through"
pedestal type specially designed for this sort of application. Many places sell them or if you are a
budding potter , have a go! You will also need a chute to connect the toilet pedestal to the barrel , this
has to be the right size diameter (~400mm) to match your pedestal, smooth on the inside , and long
enough to reach down to the barrel. Lastly you will need a 10w solar panel. ( Not an orange one ! ) I'm
still waiting for the solar panel price reduction after the thin film breakthrough , which could potentially
see solar panels at 1/10 the current price, I think the fuel companies will be dropping panel prices any
day now . . . . . .
It works like this; waste is dropped from the pedestal ( your's or other organic waste ) it drops down the
chute to land on the gauze floor in the barrel. The chute and pedestal have to be wide enough so the
dropping waste will not touch the sides ( aids cleaning! ) Liquids will drop through the gauze and collect
in the bottom of the barrel. The computer fans help with the evaporation of the liquids by circulating the
air and drawing it out of the barrel and out the vent. This is an aerobic breakdown of the waste with
water vapor and carbon dioxide as the main bi-products. In this process most pathogens are killed. With
the correct moisture levels, oxygen supply and temperature the waste decomposes to a compost ready
for the garden. With this system a useful bi-product is generated and literally tens of thousands of litres
of clean drinking water per household is saved every year.
A more in depth look: There is basically two types of decomposition we are interested in, Anaerobic and
Aerobic. Anaerobic decomposition uses bacteria that survive without oxygen, the decomposition
produces methane and sulphur dioxide gases. ( So if you throw a cigarette down the chute and it blows
up in your face , your using the wrong de-composition method! ) This system uses aerobic
decomposition, using bacteria that survives in oxygen. ( they can survive in O2 levels as low as 0.5% )
Some systems move or rotate the waste to aerate it, this speeds the decomposition process up, this
system doesn't require that . An optimum temperature and moisture level (~ 50% ) needs to be fostered
to enhance decomposition. At 4deg. virtually no activity takes place, at 20 to 40 degrees the mesophyllic
bacteria work. As the temperature rises above 40 degrees, mesophyllic populations are replace by
thermophilic populations. This stage produces the fastest decomposition. In the later stages of
decomposition, the mesophyllic organisms which are still present in the cooler outer surfaces of the
waste pile move back to the centre. Most pathogens are killed in the composts thermophilic stage which
rises above 55 degrees. So checking the temperature and consistency of the compost is a good way of
checking if it has converted properly. The correct moisture content / humidity level is attained by first
separating the liquids via the "mesh floor" . This allows oxygen to be drawn into the waste as liquid is
removed, preventing anaerobic decomposition. The humidity level is maintained by having a pool of
liquid below the solid wastes in a "closed" system. ( Below 40% the waste will "dry" and not decompose
rapidly, above 60% there is a possibility of anaerobic decomposition because of oxygen starvation due
to saturated liquids. - you will know as "rotten egg" gas is produced . ) The pickle barrel is made from a
thick black plastic which absorbs radiant heat and aids in composting and the correct humidity as well.

It is very important to maintain a good environment for bacteria. ( just as you have to for septic
systems ). Don't put any inhibitory substances into the waste such as disinfectants, and other chemicals.
If the PH levels are upset the decomposition process can stop too. Give them plenty of carbo's and
oxygen and they will do the rest. You can throw any organic substances down there, just as you would
treat a "normal" compost heap. Ladies sanitary products and the like should be disposed of else where
as it takes up needless space and is slow to decompose. It is a good idea to "kick start" your toilet with
some old compost , from the last batch, or if your just starting, use some commercial mushroom
compost or similar. It is also a good idea to put straw , grass etc on the mesh floor as this will also help
to separate solids from liquids. You can also introduce worms into the system as well to further aid in
decomposition. Red , tiger worms etc will multiply rapidly in a 20 - 30 degree environment, eggs hatch in
about 21 days, and 1 worm produces about 150 per year. The population will "balance" to their food
supply . (They will re-treat to the outer surfaces when it gets to hot. ). They have a "sweet tooth" and will
thrive on spoiled fruits, skins, molasses or plain granular sugar. Aristotle called them the intestines of the
soil, and they will produce casts "richer" than what they ingest and their own weight in casts every 24
hours.
Construction: The system doesn't have to "exacting", The important bit is to get the "environment "right
for composting. The gauze floor sits about 140mm from the bottom of the barrel on the reo table ( see
diag ) , The gauze is a good fit to the barrel at "this" height" ( stop solids falling into liquids ) The
"sucking" vent is positioned 10mm or so below the gauze floor and the liquid overflow is about 60mm
above the barrel bottom. The chute is a snug fit into the pickle barrel lid so the system is effectively
"closed", with the toilet seat down. Oh, this will please the ladies, the seat HAS to be closed at all times
unless using it. It may be an idea to install a "time back on" switch to turn the fan off while the user feeds
the little critters, as the down draft may "bother" some people. This "downdraft" negative pressure also
keeps odors from rising so the "toilet" smells "fresh". The fan assembly is open to changes too. If your
fan is too big to fit inside the 100mm pipe you will have to build a box for it with the pipe connections to
that. Remember to use gauze (fly screen ) to stop insects getting into the system. ( you don't want too
breed flies! - and this won't happen if you keep the lid down and insect baffle the vents. ) The absorption
trench is built per your countries building codes, usually a 20 metre long gravel trench. (Australia - AS
1547-1994 ), In the event of a high fluid intake the overflow conducts the excess away , this should not
normally happen as evaporation takes care of most fluids. - The diagrams convey the gist of things,
good luck.

The unit will probably last a couple of people 9 months before it fills and will require changing,
depending on usage. You will need to install an empty "pickle" barrel and re-connect the pipes. The
barrel will be very heavy to move so have one of those "material handling" two wheel trollies there to
help you shift it. The "full" pickle barrel will need to stand for a further 9 months to complete the
decomposition process, it is best if you place it in a "warm" position. Another computer fan will need to
be attached to the "standing" barrel. You may note that the "working barrel " fan and the "standing
barrel" fan are identical for obvious reasons. Having a spare or two is also a good idea even though they
last for a few years. You may even have to resort to a second "standing" barrel if your usage is fairly
high . The final 2 phases of composting take place now, the cooling and curing phase. The cooling
phase is important to because the funguses have a go at things. They are able to breakdown the
"harder" organic materials. The curing period provides a margin of extra safety for the pathogens to die
out. If you haven't introduced worms to the system , this "standing" phase would be a good time. Have a
look from time to time , turn the compost over if necessary, and apply to the garden when it's ready.
Human waste is high in nitrogen (6% dry weight ) and carbon ( 50% carbon dry weight,
Carbon /Nitrogen ratio 6-10 ) , it is closest to fowl manure as a comparison , so don't burn your plants.

When you consider the tens of thousands of litres of clean water required for flushing the toilet per
household per year ; the more than double that of grey water that is used to additionally flush the pipes
and dilute sewerage. The staggering amount of clean rainwater collected on every household's roof that
goes down the gutter and wasted . . . , It is little wonder we have water problems. It is clearly
unsustainable !

Disclaimer : Finally I have to say, If you build this it is entirely your responsibility. Ensure it follows "your"
building codes and it is made in a way to ensure life and property are protected..
Here is another system for interests sake, compost toilets that looks like the real thing!

As a final note, greywater can be used on your gardens and lawn without problems, it is advisable to
install a "skum" trap before pumping it out though. Rainwater should be caught in a tank off the house
as well, not wasted down the gutters. We might all be a little healthier if we had pure water to drink
rather than piped water that has to be "processed " to make it "safe" for consumption. - Have you ever
noticed tap water does bugger all for plants compared to natural rain. . . . . . .

A couple of LINKS to further information. . . .

WEBLIFE - This site has some on-line books, I recomend you look at HUMANURE as it covers
composting and composting toilets very thoughly ! , Excellent reading! ,"Humunure" also has a lot of
good links too, so there is no point in me providing them again.

NATURE LOO - If you just wish to buy and not build a compost toilet, this company makes a system
simular to the one described, they are here in Brisbane, provide a good professional product with
support, to get you going. ( so to speak )
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