Sanitario Seco Solar (Solar Dry Toilet)
Centro de Desarrollo del Habitat y el Medio Ambiente (CEDES/habitat)
A toilet that uses solar energy to dehydrate human excreta.
The Solar Dry Toilet was designed by Centro de Desarrollo del Habitat y el Medio Ambiente (CEDES/habitat) for farmers and indigenous communities living in remote areas in Paraguay. The toilet is designed for places with groundwater close to the surface, impermeable surfaces, and difficult access to water. The toilet uses thermal solar energy to consume pathogens and dry human waste accumulated in a 50 L container storage.
Remote areas in rural Paraguay
Goal 6: Clean water and sanitation
Households and individuals
The CEDES/habitat offers three building methods for the solar dry toilet, according to the existing conditions or the target context. The first method uses traditional masonry construction which, according to the designers, is familiar to communities and helps with introducing the toilet system.
The second method is prefabricated using cement boards and concrete poles and it is suitable for remote places with difficult access and allows for reduce-assembly time. Cement boards can eventually incorporate reinforcement increasing strength and durability.
The third method is also pre-fabricated but with fiberglass as the main material. Similar to cement boards, the fiberglass method is suitable for remote places with limited access to materials. Fiberglass is lightweight therefore transportation costs could decrease. However, disposal methods for fiberglass materials require specialized equipment that is not available in remote areas. Pre-fabrication processes facilitate quality control and production of sophisticated building components.
This product is distributed by CEDES/habitat to households and individuals living in remote areas in Paraguay.
CEDES/habitat has built around 100 solar dry toilets in different places in Paraguay.
Type of toilet
Method of evacuation
How the fecal sludge is stored
The holding volume of the containment
Time until emptying is estimated to be needed
The solar dry toilet has two main components, the cabin and dehydration container storage. Both components can be built with the same materials (e.g., masonry walls) or a combination of prefabricated and on-site building methods (e.g., prefabricated container storage and masonry cabin).
The layout of the cabin consists of a rectangular space of 1 x 1.5 m and 2.2 m ceiling height. The floor level of the cabin interior is 45 cm elevated from the ground. The material for the roof varies depending on the context, being the most common solution corrugated metal panels. The door of the cabin can also be fabricated with metal panels or wood panels and the window can be made with tilted bricks (in the case of the masonry building system) or with a metal frame.
The dehydration container storage is formed by the sanitary slab/seat and container itself. The sanitary seat is prefabricated with reinforced concrete and its design separates urine from excreta. An additional wood lid can be used to cover the slab hole to avoid bad smells. The container storage measures approximately 1.3 x 1 x 0.85 m in height. The base of the container storage is leveled with the existing ground. A vital component of the container storage is the exterior cover. This component is made of a steel frame and covered with a translucent polycarbonate panel that allows sunlight to act on the storage. For the case of Paraguay, the exterior cover must be oriented to the North to gain as much sunlight as possible.
Provided by the designer.
Households or individuals with little construction experience could repair solar dry toilets built with masonry walls or replaced some parts with materials found in the local context. Replacement components for prefabricated options may be limited, though.
The exact lifetime of this product is unknown. However, buildings in Paraguay that use similar materials and building methods (ceramic bricks, concrete columns, and cement boards) can last more than ten years with adequate maintenance.
Designer specified performance target includes privacy, hygiene, durability, and low-cost.
Testing performed by the manufacturer, in collaboration with the Paraguayan government through the Servicio Nacional de Saneamiento Ambiental (SENASA) and the School of Architecture, Design, and Arts at National University of Asuncion (FADA-UNA) determined an increase of 9-10 °C above ambient temperature inside the dehydration container storage. This increase is mainly due to the use of a container cover made of translucent polycarbonate panel and its correct orientation. According to the test, this represents a 100% temperature increase compared with similar solar dry toilets tested by the Pan American Health Organization (PAHO).
No known safety hazards are related to this product.
Solar dry toilets can incorporate an exterior urinal that is attached to the cabin wall.
Rios C., S., and Gill, E., 2012, Manual de agua y saneamiento: Tecnologias apropiadas para comunidades rurales e indigenas dispersas de Boqueron y Caazapa, Asuncion, Paraguay.
The solar dry toilet was tested through the construction of a full-scale prototype at SENASA.
Audiovisual documentation of a solar dry toilet built as in an indigenous community in the Paraguayan Chaco as part of a housing program promoted by the Paraguayan government.
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