Sulabh shauchalaya
Twin-pit composting toilet
Born in Across India.
How it works
Two leach pits are used alternately: one fills while the other rests sealed. In a year or two the rested pit has composted into dry, pathogen-free soil, and the toilet needs neither a sewer line nor a tanker, ever.
In a modern home
The default rural sanitation design under Swachh Bharat; the alternating-pit principle also runs community composting, where no pile is disturbed while it cures.
What it answers
Source
Sulabh International twin-pit design; SBM (Gramin) technical guidelines.