PIT EMPTYING SYSTEMS
Introduction
On site sanitation systems have been adopted throughout the developing world as a means of
reaching sanitation coverage targets. A growing concern surrounds how these facilities can be
effectively emptied. This becomes increasingly important in densely populated urban areas
where the practice of covering a full latrine and relocating the superstructure is often not
possible. Furthermore, access to latrines using large motorised vacuum tankers is becoming
increasingly difficult; if these vehicles are even available at all. In rural areas relocating a
latrine will often provide a safer and more financially viable solution than emptying it,
especially in remote areas where mechanical equipment is not present.
This technical brief describes the main technology categories used for emptying on-site
sanitation facilities, whilst highlighting their benefits and disadvantages. Prior to this
description of technologies, a background is given into how emptying can be planned for
during the inception phase of a sanitation project and a background into the wider issue of
faecal sludge management (FSM).
Planning for Emptying of Sanitation Facilities
As with many technologies and practices, emptying is likely to depend greatly on the area
where the latrine is located. This section will explain the affect sanitation facility type,
groundwater conditions, filling rates and composition can have on the frequency and cost of
emptying.
Prior to construction of sanitation facilities there are a number of considerations that can be
made in an attempt to simplify the emptying process. One important note is that any spillage
of excreta during emptying is likely to affect the health of not only workers, but also the
nearby community as the pathogens contained within the excreta can be transmitted by flies
(Franceys et al, 1992). Care must be taken at all stages whilst emptying to keep equipment
and the surrounding area clean.
The constructed facility should always be located close to a household plot boundary,
preferably close to the nearest access point. However, when citing a latrine/septic tank the
facility should be located downwind of the property to prevent unpleasant odours in the
household. If it is not possible to meet both criteria it is important to provide adequate access
and ensure workers or hoses will not have to travel through the household.
Sanitation Facility Type
The different sanitation systems have been described in the technical brief ‘Types of toilet
and their suitability’. Of these, the only systems requiring emptying are those which fall into
the on-site sanitation category e.g. pit latrines, pour flush latrines, septic tanks. Note that
although ecological sanitation (ecosan) systems also requiring emptying, if the system has
been operated correctly (refer to technical brief ‘Ecological Sanitation: A Concept’) then the
waste can be removed with less caution as its lower pathogen content poses less of a health
risk. Pit latrines are emptied when the sludge rises to within half a metre of the top of a
latrine. Below are some important criteria to consider before selecting a sanitation type.
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