Regarding those corbelled pit latrines in Malawi that Rochelle mentioned, there is also a previous thread here where we discussed them a little bit:
forum.susana.org/183-monitoring-and-eval...zu-university-malawi

Hi Ester,
In Malawi for unstable soils (to prevent pit latrine collapse in rural areas) we have developed the corbelled pit latrine design, which is a local innovation for a liner in a way. It is designed for household use. Here are a couple of reports on our work. Please contact me directly if there is anything else I have help with for technical specifications.

Holm, R., Tembo, M., Njera, D., Kasulo, V., Malota, M., Chipeta, W., Singini, W. and Mchenga, J. Adopters and non-adopters of low-cost household latrines: A study of corbelled pit latrines in 15 districts of Malawi. Sustainability, 2016, 8, 917. DOI:10.3390/su8100917 www.mdpi.com/2071-1050/8/10/917/htm

Chidya, R. C. G., Holm, R. H., Tembo, M., Cole, B., Workneh, P. and Kanyama, J. Testing methods for new pit latrine designs in rural and peri-urban areas of Malawi where conventional testing is difficult to employ. Environmental Science Water Research & Technology, 2016, 2, pages 726–732. DOI: 10.1039/c5ew00246j pubs.rsc.org/en/content/articlelanding/2.../unauth#!divAbstract

Kasulo, V., Holm, R., Tembo, M., Singini, W. and Mchenga, J. Enhancing sustainable sanitation through capacity building and rural sanitation marketing in Malawi. Environment Development and Sustainability, 2018. DOI: 10.1007/s10668-018-0191-2 rdcu.be/VcJZ

Hello sanitation experts of SuSanA,

Im am looking for some documentation and evidence around pit latrine liners, this is specifically for areas will collapsing soils, black cotton soil and for trench latrines.

Oxfam is looking at updating some technical guidance on this, so it would be great to have some examples of different approaches that have been carried out in the field.

Thanks
Esther