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Pour flush latrineA pour flush latrine uses water to transport excreta from the receptacle to the disposal pit.There is a water seal which makes it hygienic. The pit is provided either at the lower side of the latrine or under the receptacle (Figure5.10). It is therefore more like the water carriage system, but instead of using the flushingapparatus, water is poured into the receptacle, to push excreta into the pit. This is a system that is very convenient where there is no adequate piped water. It is also convenient for those persons who use water for anal cleaning.
The system components comprise of a flush bowl or receptacle, a pit and a superstructure. Apour flush bowl or receptacle may or may not be of pedestal type. Water forms a seal in the trap below the bowl and is an integral part of the bowl. The receiving pit may be directly below the bowl or a few metres from the latrine. Two pitsmay be provided to be used alternately. Where pits are located away from the toilet, a discharge pipe is provided. The superstructureshould have all the requirements of a pit latrine.The seal underneath the bowl traps water and prevents foul gases from escaping through thebowl to the latrine. After defecation, a litre of water is poured into the bowl. This water pushes the excreta into the pit leaving a little behind to form the seal in the trap.Two pits are used alternately, so that while one is in use, the other is resting. When the pit fills up with sludge, it is then closed and the other pit opened.The excreta in the pit are broken down anaerobically while the liquid part of the wastepercolates into the ground. To prevent water logging, there should be plenty of spacebetween the two pits.PitTwo pits should be provided to be used alternately. It takes about 2 years before a pit needs emptying. The pit may be provided directly underthe bowl or a few metres away. It must be located away from any underground source of drinking water. The volume of the pit is determined by the number of people using it, accumulation rate(0.02-0.06 cubic m per person per year) and the number of years the pits is to be used beforefilling up. The distance between pits should be as far as possible and never less than their effectivedepth or 1 m, whichever is greater. Pits should be lined to their full depth with bricks, stone or concrete. Open joints or leaching holes must be provided to allow water seepage into the ground. Where the water table is high, over-the-ground pits or tanks may be provided.CoverThe pit is usually covered with a reinforced concrete slab with a bowl placed at the centre of15
the slab.Bowl, pan or receptacleThe bowl is usually 450 mm long and about 200 mm wide and oval or pear-shaped.