Ventilated improved pit latrines : vent pipe design guidelines

This technical note sets out preliminary guidelines for the design and construction of vent pipes for ventilated improved pit (VIP) latrines. These guidelines are based on extensive fieldwork, done in Botswana and Zimbabwe in 1981-82, which showed that the local wind speed and direction were the major factors responsible for inducing updraught in the vent pipe; thermally induced updraught was found to be of only minor importance.