If the soil in which a pit is dug is stable when wet and dry, the size can be large enough to last for many years. I have looked down large pits that have used by African families for more than twenty years. The accumulated excreta was still two or three metres below the top. Standard' designs by external agencies often show these made of bricks, concrete rings or mass concrete, but in many locations cheaper locally-available material is used. In a village near Mysore latrines with the same design were built for 750 rupees.
Excavation is difficult where a pit latrine is built on rock or boulders.
Raising the lining and floor increases the volume available for storage of solids. A compensation is the use of excavated rock or boulders for the lining, reducing the cost. The floor slab Crude latrines are found in some places. A couple of boards or logs are placed across the pit for users to put their feet when defecating. Where termite-resistant timber is available, an inexpensive floor can be made of logs, usually covered with a layer of gravel or mud.