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Hi
On the question of latrines, this is not my specialist field, but I have lived and worked here in East & Southern Africa for many years and I can tell you what I have observed in passing, as follows:
- Yes, Ventilated Improved Pit (VIP) Latrines would be the best solution. One sees these in use at schools and clinics throughout the rural areas of the region.
- From recent personal experience in Zimbabwe you could cost these at $250-$300 per unit, provided you adopt a cost-effective design and get the community to provide all the locally available materials (such as river sand) free. Therefore, with your £1800 you should easily be able to build more than one unit per ward (and I think you will need more than one).
- There is a wealth of information and advice available on the Internet, including an old, but excellent, World Bank report that will tell you all you need to know about the design and construction of VIP latrines: see https://www.pseau.org/outils/ouvrages/world_bank_the_design_of_ventilated_lmproved_pit_latrines_1984.pdf.
- The first step is to decide on the preferred life of the units. Obviously the longer, the better. But the longer the life, the higher the cost. My suggestion would be to start by assuming a required life of, say, 10 years and to see how this translates to the number of standard units required vs the budget. Consider life vs the cost of emptying (but I must say I have never seen VIP latrines being emptied anywhere).
- The World Bank report tells you how to calculate the annual volume of deposit per person and how to translate this into the number of standard units required for the life required and number of people to be served.
- Points to note:
- Make sure that the interior of the cubicle is permanently dark. Do not include a door (they get left open; hinges get broken). Instead use a helical superstructure (see WB report -- unfortunately the figures in the copy I referred to are indistinct, but I am sure there are better copies available; if not, let us know).
- Don't worry about a pedestal: a hole in the cover slab is fine.
- Do NOT exclude the flue. This can be a built-in pipe or a flue built in masonry/brickwork, but in either case do NOT exclude the fly screen.
- Do NOT leave a gap between the walls and roof (or windows/wall vents/any other source of interior light).
Good luck!
Tony
