Eco lo g i c a l To i l e t s 125
Farmers make compost from food scraps and animal manure and add it to
the soil. This keeps the soil full of nutrients for growing crops. Just as people
need nutrients from food to grow strong and healthy, plants need nutrients in
soil to grow strong and bear fruit.
Fertilizer can also be made from human waste. Human waste contains
nutrients that can be used to improve soil. But it also carries germs that cause
disease. For this reason, making fertilizer from human waste takes more care
than composting animal manure and food scraps.
Feces should never be used fresh. But once made into fertilizer, feces safely
help grow food, trees, and other crops without chemical fertilizers.
Urine carries fewer germs than feces and has more nutrients than feces.
This makes it safer to handle and very valuable as fertilizer. But urine is too
strong to use directly on plants, and also needs special treatment first (see
page 134).
Compost toilets and urine diverting dry toilets
There are 2 main types of ecological toilets: ‘compost toilets’ and ‘urine-
diverting’ or ‘dry’ toilets. Both of these can create safe fertilizer. Many people
call both of these toilets ‘compost toilets.’ But there are some important
differences.
In compost toilets:
• Feces and urine go into a
container, like a shallow pit or
a large concrete box that will
not leak into the groundwater.
• The user adds a mix of dry
matter such as straw, leaves,
sawdust, soil and ash after
each use. This reduces smells
and helps the waste break
down and become compost.
• Time will kill most germs,
including roundworm eggs
(the hardest to kill).
• After the mix has had a long
time to kill germs in the
feces (usually 1 year), the dry
matter is removed for use as
fertilizer.
In dry toilets:
• Urine is kept separate from feces
(see page 129). It is collected,
processed, and used as fertilizer.
• Feces go into a container, like
a large concrete box or a hard
plastic movable container that
will not leak into groundwater.
• The user adds soil mixed with dry
plant matter and ash to the feces
after each use. This reduces smells
and helps the waste dry out.
• The feces never get mixed with
water. A dry mix will kill most
germs, including roundworm eggs.
• The feces are stored for up to
1 year, until it has the texture of
dry soil.
For both of these toilets, the aged feces mixture is ready after a year to be
mixed into a compost pile, emptied into a shallow pit for planting a tree, or
added directly into the soil for planting.
A Community Guide to Environmental Health 2012