Hesperian Health Guides

Pour Flush Pit Toilets

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HealthWiki > A Community Guide to Environmental Health > Chapter 7: Building Toilets > Pour Flush Pit Toilets

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water seal trap
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water seal trap set in concrete platform

Pour flush toilets use water to flush waste into a pit. These toilets are common in both urban and rural areas where water is used to clean the anus after defecating. They are not much more costly than pit toilets. Because well built pour flush toilets prevent smells, they can be built in or near the home.

Pour flush toilets use a plastic, fiberglass, or cement bowl or squatting pan set into a concrete platform. The bowl or pan often has a ‘water seal trap’ that prevents smells and insect breeding in the wet pits. The concrete platform is placed directly over a pit. Or it can be connected by pipe to 1 or 2 pits.

How to use a pour flush toilet

When there is 1 pit, the toilet is used until full, and then it must be emptied before it can continue to be used. When there are 2 pits, there is a junction box that directs waste towards the pit in use. The first pit is used until near full. Then waste is diverted into the second pit.

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The pipe to the pit not in use is sealed with a brick, clay, or fabric plug.
Waste flow
Concrete channel inside junction box directs wastewater.
1 pit pour flush toilet
2 pit pour flush toilet
Junction box
Junction box made of brick outside, and smooth cement mortar on the inside.
One lined pit underground, 2 meters deep. A family of 5 will fill this pit in about 5 years time.
Above ground chamber allows wastewater to flow down to pits. With regular care, this toilet will last many, many years.

When building a 2 pit pour flush toilet

Depending on soil conditions and groundwater level, pour flush toilets should never be built less than 3 meters from wells. In wet soil conditions the toilets should be at least 20 meters from wells.

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Pit shape: pits can be any shape, but round pits are the least costly and most stable.
Pit lining should be brick or stone, with spaces left for liquids to drain out.
The distance between pits should be at least the same as the depth of the pits. If the pits are 1 meter deep, they should be at least 1 meter apart.
Pits should be covered with reinforced concrete slabs, stone slabs, or wooden planks. The concrete platform, without a hole in the middle, could make a good pit cover.

To maintain a pour flush toilet

Water must be poured in after every use. Pouring a little water in before using will also help keep the pan clean. Clean the toilet daily. To clean the squatting pan, use detergent powder and a long handled brush. The pits can overflow if:

  • the water seal gets blocked. If this happens, the toilet will not work.
  • the groundwater is less than 3 meters deep. When this is true, there is also a risk of groundwater contamination.

Emptying the pit

If the pits are built well and soil conditions and moisture are favorable, the waste will slowly and safely absorb into the surrounding soil, and the pits should not need emptying.

If waste does not decompose and absorb into the soil, the pit will need emptying. Remove the pit cover, add a layer of soil about 30 cm (2 handwidths) deep, and replace the cover. After 2 years, the contents can be removed with a shovel and used as fertilizer.