1. Nirmalgram, Nasik
(Not to be confused with govt's nirmalgram program which started much
later) They've done good work on eco-friendly, sustainable and useful
I stayed there recently. We used normal-looking indoor toilets inside
the dormitories, and found out later on that rather than going into
drainage or septic tank, they lead to 2-pit compost systems that
convert the excreta into manure and this manure is used in the organic
farm located at this place. First time I used modern, clean, indoor
toilets that create manure rather than disposing of it toxically.
Previously, in Auroville I've used, and cleaned out, a compost toilet
located outside the residence which is a little difficult /
inconvenient to use; but these at Nirmalgram were just like simple
modern toilets and till our last day there we had no clue it wasn't
going into the typical drainage / septic tank.
2. Safai Vidyalay, Ahmedabad
I've visited them twice; again, inspiring work, and the technologies
they've researched and published (openly) really ought to be adopted
on a large scale.
Both these places conduct tours, trainings and have a "toilet museum"
on their premises where we can see all the models for real.