Dry Toilets

The main benefit of a dry toilets is the economy of water. Water conservation and recycling is becoming the next challenge of the 21st century. If you live in a humid area you can afford recycling brown water using a bio-digestor with evapo-transpiration, if not, the dry toilets is the best practice you may settle to reduce water usage.

They are other benefits (or specificity which can be considered as benefits depending on the objective) such as;

– creation of compost in a aerobic way (no methane production)
– compacting of residues (a dry compost chamber of 1m3 can handle few thousands of utilization before to be emptied)
– urine and feces separation for direct urine usage as organic fertilizer

Here is a step by step construction of a dry toilets with urine and feces separation (urine diversion).

A wooden structure is prepared using mortises.

and ankles.

Positioned on the ground,

leveled and cemented on the floor to increase stability and protect the wood from decomposition.

2 chambers for the feces are built with boards, made of recycled packaging, on the ground. 1 chamber will be used and when full will be closed for letting the compost to mature. The other chamber will be then used, and so on with regular rotation.

The roofs are made in order to protect the edifice and work as well when raining. The cabin is located on the first floor. The dry toilets is located in an area with sea view and sea breeze. Later on trees will surround the construction to add cool down and better integrate the dry toilets in the landscape. The transparent roof plays a role in letting the sun come through and keep the place dry, reducing moisture for hygienic reason.

The urine gutter diverts the flow to a banana circle beside the dry toilets.

Here is a view of the banana circle at start.

The bench is simply made and both the cabin and the feces chamber are very well ventilated. This ventilation provide with comfort and speed up the process of feces drying.

The gutter is better made of zinc (vs plastic) to handle energetic maintenance. The zinc allows as well to be slightly reshaped in order to ease the positioning of the gutter with regard to urine feces separation accordingly to human morphology. Here an old gutter has been reused. The feedback I have from female users is positive when it comes to pee in the gutter.

After every usage a large handful of leaves is thrown of the feces to complement the compost (with carbohydrates) and speed the drying process. In case of smell, meaning anaerobic decomposition due to humidity excess, more leaves need to be added.

A sink is added for hygiene.

After 6 month of use the small banana trees have benefited from the urine recycling and reach now the top of the roof.

An explanation board is there to optionally learn Portuguese from brazil.

Some tips about dry toilets;

– mixing urine and feces may increase bacteriologic activity (quicker composting) but will produce more smell

– when you build your dry toilets think “big” enough. People who have made very small compartment end up carrying the humanure to the compost pile every day or half-week, including the production from visitors. Usually they do not see this as a nice experience. In the example shown here there is no handling of feces. Only handling of earthy compost done after 6 or 9 months of maturation.

– The compost chambers should be located at ground level for easy access. The bottom of the chambers may be insulated so that no feces parasites/worms can infiltrate the ground before the composting phase start. This is mandatory in a place where people walk barefoot.

– If you integrate the compost chamber into your house study first the ventilation process and the prevailing wind direction mainly during the humid season.

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