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The available sanitation options can be divided into broad categories for planning purposes. The basic choices are between wet and dry systems and between those which retain faecal material on or near the plot and those which remove it from the plot. Until recently the common practice in most low-income urban areas in South Asia was the use of dry latrines which sometimes incorporate containers which turn them into crude bucket latrines (Pickford, 1983). Such latrines present obvious health hazards. In recent years, there has been a general move towards the use of pour-flush latrines which, while improving on-plot sanitary conditions, also introduce the need for satisfactory effluent disposal. Disposal of latrine effluents to leach pits or soakaways, situated on or adjacent to plots, is possible where plot sizes are not too small and this option has the advantage that the effluent is contained on site and so does not pollute receiving water courses. The double pit design has been widely promoted in India and elsewhere, but it requires more of the householder than other options; Cotton and Franceys (1987) suggest that users do not always understand the principles upon which it is based. Experience with a scheme which preceded those in the Peshawar Cantonment which are described later in this chapter supports this view. Many householders have concreted over the coverslabs of the pits together with, in at least one case, with the flow division chamber. A disadvantage of all on-plot options is that they can only deal with very limited amounts of sullage water. In the Baldia area in Karachi, Pakistan, for instance, a project to dispose of WC effluents to leach pits, although initially successful, experienced some difficulties when the water supply was improved so that sullage water began to collect in streets and a rise in the water table resulted in flooding of the leach pits (Pickford, 1990). |
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In low-income areas in Pakistan, householders commonly connect WCs to individual septic tanks located in the lane or street outside their houses from which effluent is discharged to open drains. While this practice is better than that of discharging effluents directly to open drains, there must be questions about the fact that the effluent is highly contaminated with pathogens, even after passing through the septic tanks. Sewers would appear to offer a better option than open drains and the experiences of |
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