Redesigning the ventilated improved pit latrine for use in built-up low-income settings

Abstract

The ventilated improved pit (VIP) latrine has the potential to address the challenge of access to improved sanitation in built-up low-income settings. However, its conventional technical design fails to address the needs and preferences of some users. The objective of this paper was to test the technical performance of modified engineering designs of the technology to respond to some preferences of toilet users. The entry of air from multiple windows in the superstructure and installation of insect screens in windows were tested in an experimental VIP latrine. The modified design achieved the recommended ventilation rate of 20 m3/h when a vent pipe diameter of 150 mm was used. The study concludes that adopting a multidirectional airflow design leads to a lower ventilation rate as compared to the conventional design. However, when fitted with the recommended size of vent pipe, this modified design achieves more than twice the recommended ventilation rate with or without an insect screen installed in the windows. Nevertheless, the practice in which 100 mm diameter vent pipes are used with insect screens installed in windows is likely to lead to odour problems due to inadequate ventilation through the vent pipe.