National Water Supply and Sanitation Council
Baseline Study
Improved Pit Latrine
Level:
Dry on-site system
Next component technology options
Ventilated improved pit latrine, pour-flush pit latrine, double pit
system
Air vent
Latrine shelter designed and built with
appropriate local
materials
Mound of excavated
soil to seal pit lining
and to prevent flooding
of pit by surface water
Gases escape
into the atmosphere
Latrine slab of concrete at least 0.15 m
above ground level (to prevent flooding)
with hole, preferably covered with a
tight-fitting lid when not in use (to reduce
smells and to keep insects out of the pit)
Pit lining extends at least
1.0 m below ground level
(deeper if soil is unstable
or pit will be emptied)
Pit should be at least 2 m
deep and 1 to 1.5 m
round or square
Solid residue
decomposes and
accumulates
Description:
A top-structure over a pit. The pit may be lined (recommended where emptying is required), or unlined
where soil conditions allow.
Principles of operation:
Waste drops into the pit where organic material decomposes and liquids percolate into the surrounding soil.
The defecation hole should be covered to keep insects away from the pit. A separate hand washing facility
is required.
Operational and institutional requirements:
Locate to prevent ingress of storm water into the pit, as well as in consideration of local groundwater use
and conditions. Pits should be at least 15 to 30 metres from sources (well, hand pumps) of drinking water
(depending on local hydro-geological conditions). When groundwater levels are high, or when the soil is too
hard to dig, the pit latrine may have to be raised above ground level.
Appropriate anal cleansing materials and a hand washing facility should be available in or near the latrine.
Does not accept domestic wastewater. Cannot be placed inside the house. Ensure access for mechanical
pit-emptying and availability of sludge treatment and disposal are required.
Costs:
Actual costs will depend on: the pit volume, the quality of pit lining, slab and superstructure, whether materials are available locally, and the local costs of materials and labour. Costs are estimated between €
30 and € 140. The cost for pit lining and superstructure can account for up to 85%, if the pit is fully lined
and the superstructure is constructed with sand-cement blocks. Operation and maintenance account for
around 1% of the investment costs per year.
Experience and comment:
Preferably used as a household facility in peri-urban and rural areas of Zambia. Failures generally due to
poor design and construction. Costly adaptations can required where shallow rock or shallow water tables
occur. Usually pit emptying is not carried out.
IMPLEMENTATION
TECHNICAL
ADVANTAGES
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O&M
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Does not require water.
Does not require electricity.
Can be built by the household.
Easy to build locally with commonly available materials.
No permanent superstructure required.
Low construction skills needed.
Municipal involvement can be limited to design and maintenance guidelines.
Small land requirement on plot.
Easily understood by the household.
System is robust with little day-to-day attention required
other than cleaning.
DISADVANTAGES
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OTHERS
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Cheapest sanitation option - least investment cost.
Accepts any form of anal cleaning material.
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Toilet can not be inside the house.
Separate sullage disposal facility required.
Pits must be 15 – 30 metres away from ground and surface water sources.
Groundwater table must be about 1.0 m below soak-away pit.
Requires stable soil conditions and soil permeability of  10-7 m/sec.
Pits often fill up too quickly in soils with low infiltration and leaching capacity or if the water
table reaches into the pit.
Risk of clogging and overflow.
In hard soils it may be impossible to dig.
Needs full lining to the bottom if it has to be emptied.
No permanent solution because new pit must be dug every few years if it is not emptied.
Not suitable for flood prone areas.
Badly-sited latrines can get flooded or undermined.
Need to keep defecation hole covered with a tight fitting lid.
To be a permanent solution periodic desludging is required:
 Access for emptying services or manually emptying is necessary.
 Sludge needs careful handling if it has not been left to decompose for at least one year.
 Vacuum tankers may not be able to deal with consolidated pit latrine sludge.
 Requires septic sludge transportation and safe disposal.
Non-biodegradable materials (stones, glass, plastic, rags etc. ) should not be thrown into the
pit, as they reduce the effective volume of the pit and hinder mechanical emptying
Excreta may be visible.
Possibility of smells.
Nuisance through flies and cockroaches.
Does not control mosquitoes.
Children may be afraid of using the latrine if the latrine is dark and the drop hole too big.
If abandoned pit must be covered with 0.5 m of top soil to hygienically seal it off.
Effluent may contaminate groundwater.