Reed Odourless Earth Closet

Design consideration for ROEC

Design life

Most likely 4 to 15 years but the design life should be as long as possible: at least 10 years is desirable. The longer the design life, the longer the interval between relocating or emptying the latrine.

Dimensions

Usually the pit cross-sectional area should not be more than 2 m2 in order to avoid cover spans with large spans. In practice, a ROEC serving one household commonly has a diameter of 1–1.5 m or in case of square or rectangular pits, a width of 1–1.5 m.

Vent pipe

Vent pipe of a wide variety of materials are used, for example polyvinyl chloride (PVC), unplasticized PVC, bricks, etc. Whatever material is used, durability (including corrosion resistance), availability, cost and ease of construction are important factors. The vent pipe is sufficiently long such that the roof does not interfere with the action of wind across the top of the vent pipe. For both flat and sloped roofs, the top of the vent pipe should be at least 500 mm higher than highest point of the roof.

The internal diameter of the vent pipe depends on the required venting velocity necessary to achieve the recommended ventilation rate of at least 20 m3/h. This in turn depends on factors like internal surface roughness of the pipe, its length (which determines the friction losses), the head loss through the flyscreen and wind direction.

Flyscreen specification

The purpose of the flyscreen is to prevent passage of flies and mosquitoes; therefore, the mesh is not larger than 1.2 mm × 1.5 mm. The flyscreen is made of corrosion-resistant material that is able to withstand intense rainfall, high temperature and strong sunlight. Stainless steel screens are preferred.

Advantages

As the pit is offset from the squatting hole excreta will not be seen, thus convenient to the users.

References

• Workshop on community management of waste water (treatment and disposal)