Designing the Easy Latrine

Posted in — Cambodia Sanitation > Design
February 5, 2019
3131 Idecam Latrine Schematic
iDE Global WASH

How to create an affordable, attractive product that poor households want to buy and use.

Before iDE launched the Easy Latrine, the existing sanitation options for rural Cambodians did little to drive increased improved sanitation coverage. For most households, the available options were open defecation, unstable dry pits, and expensive concrete bathrooms. iDE set out to design a marketable toilet that could be easily manufactured by local producers that was also attractive and affordable for poor rural customers. We aimed for a sustainable latrine: one that would not collapse, would not degrade year after year, would not fill up prematurely, and would not be abandoned. iDE recruited Jeff Chapin, while he was on sabbatical from IDEO, to help design the latrine.

Using a human-centered design (HCD) approach, we identified the unique needs, desires and barriers of rural Cambodian users and produced a product that households wanted to buy and businesses wanted to sell, creating a sustainable solution that could be scaled across the country.

Insight: The patience to save money and invest is remarkable. Villagers will save for a lifetime to build a house and may save 3-6 years to build a latrine.

The Design Process

The team began by interviewing customers, manufacturers, and others involved in the sanitation supply chain and related fields, such as concrete manufacturing. The learnings from our research were distilled and synthesized to understand how our latrine design compares with other options on the market. After multiple iterations, a design direction emerged that addressed user needs as well as marketing insights around how to position the value of latrine ownership.

Insight: Grown children who have emigrated to the city or work in a factory with latrines often motivate their parents to build a latrine and may help finance the latrine.

Prototype Reviews

In the course of the design project, iDE took four trips to the field after the initial user research to review prototypes with stakeholders: villagers (users), masons (installers), ring producers (manufacturers), and retailers (sellers). The team gathered feedback using 2-D and 3-D prototype scale models to understand households’ understanding of the latrine features. Posters illustrated six different upgrade paths and a set of 1/5th-scale prototypes with which each of the upgrade paths could be constructed. Each path had a different starting point (e.g., dry pit, wet pit, offset pit, direct pit, concrete shelter, bamboo shelter, etc.) and different number of steps to completion, to assess how many upgrade steps were ideal and how well the villagers could fill in the gaps in the upgrade paths. A transparency with a natural shelter printed on it was overlaid on the early steps to illustrate that a self-built, locally-gathered natural shelter would be used in the early stages before enough money was saved to build a concrete shelter.

Later prototypes built on this feedback, focusing on:

  • User understanding of the pan stand concept,
  • Ring producer concerns with the pan stand, thin ring and tapered ring concepts,
  • Ring producer feedback on potential mold designs and casting methods,
  • Ring producer and villager expression of the potential benefits of the ideas proposed, and
  • Transportation costs and cost drivers for concrete rings and slabs.

Along the way, many ideas were abandoned in the process: blow molded pit linings; expanded polystyrene pit linings; fused rubber chip rings; foamed concrete rings; pervious concrete rings; brick aggregate concrete rings; precast concrete shelter walls; extruded plastic shelter walls; plastic forms for cast-in-place concrete rings, slabs and walls; rice husk ash concrete; roll-up concrete textiles for lining pits, among others. While the list is long, it illustrates the complexity of design in even something as simple as a household latrine. The design process ultimately resulted in the Easy Latrine - an affordable, improved latrine that meets households’ needs and desires. The research also identified critical opportunities for iDE to educate supply chain actors in how to manufacture and install improved latrines.

The image below provides a picture of how customers are using the Easy Latrine from iDE’s recent customer survey. As of mid-2018, over 300,000 have been sold to rural households.

3131 Idecam Latrine Schematic