Under the twin-pit system, two pits are dug with honeycombed walls and earthen floors which allow liquid to percolate into the surrounding soil
Links:
[1] http://admin.indiaenvironmentportal.org.in/news/only-26-rural-toilets-use-twin-leach-pits-finds-survey
[2] http://admin.indiaenvironmentportal.org.in/category/author/varun-b-krishnan
[3] http://admin.indiaenvironmentportal.org.in/category/newspaper/hindu-new-delhi
[4] http://admin.indiaenvironmentportal.org.in/category/thesaurus/open-defecation
[5] http://admin.indiaenvironmentportal.org.in/category/thesaurus/toilets
[6] http://admin.indiaenvironmentportal.org.in/category/thesaurus/twin-pit-toilets
[7] http://admin.indiaenvironmentportal.org.in/category/thesaurus/centre-science-and-environment-cse
[8] http://admin.indiaenvironmentportal.org.in/category/thesaurus/sanitation
[9] http://admin.indiaenvironmentportal.org.in/category/thesaurus/rural-sanitation