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Ecological Toilets

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HealthWiki > A Community Guide to Environmental Health > Chapter 7: Building Toilets > Ecological Toilets


Ecological toilets turn feces and urine into soil conditioner and fertilizer. This improves people’s health and the environment by preventing the spread of germs and turning harmful waste into a valuable resource.

Ecological toilets also protect and conserve water because no water is needed for their use, except for washing. They are safer for groundwater than other toilets because they sit above ground or use shallow pits.

Ecological toilets can be built and used in cities, towns, or villages. They need more maintenance than pit toilets (but not as much as pour-flush toilets), so it is important for people to understand how they work.

Contents

Turning waste into fertilizer

Rich, healthy soil needs organic matter (what is left when plants and other living things die and decompose). This natural process of organic matter breaking down into soil is called composting.

Illustration of the below: Arrows from an ear of corn, to a woman eating, to a person in a toilet shelter, to a woman farming, to a crop of corn.
The soil grows crops
Fertilizer feeds the soil
Crops become food
Human waste can be turned into fertilizer
Food becomes human waste
Ecological sanitation turns waste into a resource.

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.

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:

  • 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.

Dry toilets help local economy
A man examines samples of toilets under a sign reading, "Sanitation Workshop Today."

In several towns in Morelos, Mexico, many people use ecological dry toilets. One neighborhood called La Cienega has a special need for dry toilets because it is in a wet, lowland area where pit toilets get flooded. To solve the problem, members of the community bought a special kind of toilet bowl that separates urine from feces. These toilet bowls are built locally in small workshops with several local workers. The workers train community groups how to use these new toilet bowls.

Many people in La Cienega make a living by growing and selling fruit trees and other plants. The first people in the neighborhood to use dry toilets discovered they could use the urine and compost from their toilets as fertilizer for the trees. When their neighbors saw the trees grow big and healthy, they too wanted to try these new toilets that give free fertilizer.

Now, almost everyone in La Cienega uses these toilets. The local workshop is busy making them, and the community has grown both healthier and wealthier.

Simple compost toilet for tree planting

This toilet makes fertilizer for planting trees. It is simple to build, and is made so the shelter can be moved when the pit is full.

This toilet is best where there is space and a desire to plant trees. It is also good for places with high groundwater, because the pit is shallow. Covering the toilet pit with soil and planting a tree there helps to decompose the waste.

This is a great way to start an orchard of fruit trees or other useful trees. If you do not plan to plant trees, use a different type of toilet.

A woman plants a small tree between a toilet shelter and some larger trees.

Build a simple toilet for tree planting

Level the ground and place a concrete ring beam where you want the toilet. Inside the ring beam, dig a pit 1 meter deep. Secure the ring beam in place. Make a platform to put over the pit and ring beam. Build a light shelter for privacy that will be easy to move.

To use and maintain this toilet

Women work together to move a toilet shelter over a platform and pit.
  • Before using, put dry leaves or straw in the pit. This will help feces decompose.
  • Add a handful of soil mixed with ashes or dry leaves after every use.
  • When the pile gets too high, stir it down with a stick.
  • Sweep and wash the platform often. Be careful not to get much water in the pit.
  • When the hole is nearly full, remove the shelter, platform, and ring beam.
  • Fill the hole with 15 cm of soil mixed with plant matter. After several weeks, the waste will settle. Add more soil and plant matter, water, and plant a tree. Fruit trees grow well and bear safe and abundant fruit.
  • Move the shelter, platform, and ring beam to another place, dig another hole, and do it again.

2 pit compost toilet

1 meter
30 cm
1 meter

The 2 pit compost toilet is like the simple compost toilet for tree planting, but instead of planting a tree in the pit, the compost is dug out and used in the garden or fields. This toilet tends to be safer for groundwater than traditional pit toilets because the waste is mixed with soil in a shallow pit, allowed to dry out and kill germs, and then removed.

To build a 2 pit compost toilet

Dig 2 pits 1 to 1½ m deep, 1m wide, and 30 cm apart. Add a lining or ring beam to both pits. Place a platform and a simple shelter over one pit, and a concrete or wood cover over the second pit. Use the first pit until it is nearly full. A family of 6 will fill the pit in about 1 year.

  1. When the first pit is almost full, fill it with 30 cm of soil and cover it with a board or concrete slab. Move the platform and shelter to the second pit. Use it until it is nearly full.
  2. Leave the first pit alone. Or, after it has settled for 2 months, add more soil and plant a seasonal vegetable like tomatoes right in the pit. Because the waste in the pit is still being processed, it is best to avoid crops that grow under the ground, such as carrots and potatoes.
  3. When the second pit is full, empty the first pit with a shovel. Wear gloves, and wash hands after handling the fresh fertilizer.
  4. Woman shoveling compost into a wheelbarrow.
    After 1 year, the contents of the 2 pit compost toilet should be safe to mix into garden soil as fertilizer. But it is still best to wear gloves and shoes when handling it.
  5. Store the dry matter from the pit in open bags or buckets for later use, or add it to a compost pile or garden. (To know when the contents are ready, see “When solid fertilizer is safe to use.”) Move the platform and shelter back to the first pit, while the contents of the second pit settle. And so on…

To maintain a 2 pit compost toilet

  • Keep a bucket of soil mixed with dry plant matter in the shelter. After each use, throw a handful in the pit.
  • When the contents of the pit get too high, stir it down with a stick.
  • Sweep and wash the platform often. Be careful not to get much water in the pit.

Urine diverting dry toilets

Dry toilets do not use pits. They are built above ground so it is easier to remove the contents. They also have a toilet bowl with separate compartments that keep urine and feces separate. This helps the contents of the toilet stay dry, which kills germs and reduces smells. This also allows the urine to be used as fertilizer. Because they are built above ground and lined on the bottom, well built dry toilets do not contaminate groundwater.

Dry toilets are more costly to build than pit toilets. Their safe use requires training, because they are used differently than pit toilets and flush toilets. And it takes some work to keep them well maintained. But they are very good for people who want to produce fertilizer from their wastes. They are also a good choice in places where:

  • The groundwater is too high for pit toilets.
  • Flooding is common.
  • The ground is too hard to dig.
  • People want a permanent toilet in or near their house.

2 chamber dry toilets

This dry toilet has 2 chambers where feces break down into safe fertilizer. One side is used as the toilet while the feces on the other side dry and break down. A special toilet bowl that works for both men and women separates urine from feces. The urine drains through a tube into a container outside of the toilet. After about a year, the dried feces are removed and added to a compost pile or used on fields or gardens. The collected urine can be mixed with water and used as fertilizer.

Parts of the 2 chamber dry toilet

Front of toilet
Back of toilet
Shelter for comfort, privacy, and to keep the toilet dry
Urine pot where the urine is collected from the toilet and the urinal
2 chambers made of brick, concrete, or other durable material. While one is in use as a toilet, feces dry and decompose in the other.
Urinal
This dry toilet bowl separates urine from feces. Home-made urine catching devices work just as well.
Small doors at the back to remove dried feces
Hose to divert urine from urinal and bowl to urine pot
3 ways to build a dry toilet

All 3 have a base made of concrete, brick, or any other waterproof material with these parts.

2 chambers
2 small doors
a vent pipe
hole for vent pipe
a hole on each side or in
the front for the urine diverting
hose to run out of the chamber
For all 3, build a shelter and steps. Attach doors in the back (concrete slabs held in place by lime mortar work well). Run the urine diverting tube out the hole in the toilet base to a container, a drainage pit, or into the garden to fertilize the soil.
TYPES OF TOILETS 1. For
squatting
2. For sitting,
with a bench...
3. ...or with a
toilet bowl
BUILDING THE BASE
Leave a space in the dividing wall for a urine separating container to serve both chambers. Cover the base with a level platform of wood or concrete with a hole over each chamber. Cover the base with a level platform of wood or concrete with a hole over each chamber.
DIVERTING THE URINE
Cut the bottom off a 20 liter water bottle. Attach it, upside-down, to the space in the wall dividing both chambers. Attach a tube to the spout to divert urine, making sure there are no leaks between the jug and the tube. Put a fine mesh screen in the jug to keep feces and other things from falling in. Cut the bottom and side from a plastic jug. Attach a tube to the spout to divert urine. Put a fine mesh screen in the jug to keep feces and other things from falling in. Urine diverting toilet bowls can be built or bought in some places. If they are available they are very easy to install and use.
FINISHING THE BASE
Cut a long squatting hole in a platform, with the upside-down bottle in the center. Urine goes into the bottle and feces into the chambers below either end of the hole. Put a cover on half of the hole, over the chamber that is not in use Attach a urine diverter to the front of each hole. Put toilet seats over the holes. Put the urine diverting toilet bowl over one of the holes and cover the other hole until it is ready to use.
BUILDING A SHELTER
container
hose
urine is collected in a container to use as fertilizer...or sent through a hose into a soakaway pit.

To use and maintain a 2 chamber dry toilet

Post information to help people use and maintain the toilet
Bottle of water. Add a little water to the urinal and the urine separator after each use, to control the smell.
Keep unused chamber covered when not in use.
Make a urinal from a plastic jug and attach a tube to carry urine to a container or drainage pit.
Paper
Keep urine
separator
screen clean.
When the
screen is blocked, remove
it, clean it, and replace it.
Pot of mixed soil, ash and dry plant matter. After each use, throw 2 handfuls down the dry part of the toilet bowl. Then close the lid.


  • Make sure no water gets in the feces holding part of the toilet chamber.
  • If the contents of the toilet get wet, add more dry matter.
  • If the toilet smells bad, add more dry matter, and make sure the vent pipe is clear.
  • If the pile of feces builds up too high, use a stick to push it down.
  • When the urine pot is full, empty it and make fertilizer.
  • When one chamber is full, use the other chamber. Be sure to cover the chamber that is not being used.
  • It is best to let the feces sit for a full year before emptying the chamber. After a year, or when the second chamber is full, empty the first chamber and repeat the process.

Do not put garbage in the toilet

Do not put garbage in the toilet

For ecological toilets to work, they must be used only for human waste. Women having monthly bleeding may safely use ecological toilets. But sanitary pads and other products should not be put in the toilet.

Ecological toilets cannot be used to dispose of things that will not break down, such as cans, bottles, plastic, tampons, or large amounts of paper. It is OK to use small amounts of paper, leaves, sawdust, and other plant matter because these things break down into soil.

When solid fertilizer is safe to use

The contents of a dry toilet are ready to remove when they are dry and have little or no smell. For this to happen, they should be kept dry inside the toilet chamber for 1 year.

When you think the contents are ready to remove, open the chamber. If the pile is wet, add dry plant matter or soil mixed with ash and let it sit for several more weeks. If the pile is dry and does not have a strong smell, it is ready. Remove it with a shovel.

Remove dry material for use as fertilizer.
It is important to wear gloves and shoes when handling human waste, and to wash well after emptying the toilet.


After drying out for 1 year, most germs will be dead and the material should be safe to add directly to garden soil. But if there is any doubt, the waste can be stored in open bags or buckets in a dry, sunny area or added it to a compost pile.


Urine fertilizer

Some farmers use urine mixed with water as a fertilizer because urine carries valuable nutrients such as nitrogen and phosphorous that can help plants grow. Urine is much safer to handle than feces. However, the same nutrients that make it a good fertilizer can pollute water sources. Also, urine can carry blood flukes. Because of this, it is important not to put urine into water sources, or near where people drink or bathe.

To make simple urine fertilizer

Store urine for a few days in a closed container. This will kill any germs the urine contains, and will also prevent nutrients from escaping into the air.

To make fertilizer, mix 3 containers of water for every 1 of urine. You can fertilize plants with watered down urine as often as 3 times a week.

3 jugs of water plus 1 jug of urine = safe fertilizer

Plants fertilized with urine can grow as well as plants grown with chemical fertilizers, and need less water. Plants that have leaves you can eat, like spinach or other dark green leafy vegetables, grow best. Always wash your hands after handling urine.

To make fermented urine fertilizer

Adding compost to urine, and letting this mixture rot and turn sour (ferment), can create new soil for planting.

  1. Collect urine from dry toilets. For each liter of urine, add 1 tablespoon of rich soil or compost.
  2. Let the mix sit uncovered for 4 weeks. This will smell bad, so do it in a place away from people. The urine mixture will ferment and turn brown.
  3. Fill a large container with dry leaves, straw, or other dry plant matter. Line the container with thick plastic to prevent water leakage through the hole in the bottom.
  4. Add fermented urine. The best mix is 7 parts plant matter to 1 part urine (about 3 liters of urine for every 30 cubic centimeters of plant matter).
  5. Cover with a thin layer of soil (no more than 10 cm). Plant seeds or seedlings.
  6. Water every 2 days with a mix of 1 part urine to 10 parts water. (This is a weaker mix than we suggest above, because it will be used in closed containers rather than in open gardens or fields.) The dry plant matter will turn to rich soil in 10 to 12 months.

The new soil can be used for planting.

Improved and adapted dry toilets

The toilets in this book are only some of the choices for ecological sanitation. They can be improved and adapted to meet the needs of different communities. Some things that will make a dry toilet work better are:

  • Heat from the sun will help the waste decompose. Build the toilet so the chamber doors face the sun, and paint the door panels black. This will make the chambers heat up, improve air flow, and kill germs faster.
  • More air flow will also help the waste decompose. Laying bamboo, corn stalks, branches, or other dry plant matter inside on the bottom of the chamber before use will help air flow through the feces for faster drying.

A wash toilet with plant bed

People in India have adapted the dry toilet to let both urine and wash water drain into a plant bed.

Ash bucket
Washing is done over a hole that drains into the plant bed.
Wash water
Feces hole
Urine hole
The plant bed where the wash water and urine go is filled with sand and gravel and planted with reeds or other local, non-edible plants. When the plants grow too big, they are cut back and thrown into the toilet.
The chambers under the toilet are lined with straw before use, to absorb moisture and make a good bed for the compost. Every time it is used, 1 or 2 handfuls of soil or ash are thrown in. Every now and then, some dry plant matter is added to help the material dry and decompose. After one year of use, the first chamber is opened and the material is put in a compost pile or into the soil for planting.


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