Sher Singh is barely 50. He wheezes as he tries to sit up in the tiny, rented room in a suburb of the Indian capital. A little over three years ago, Singh climbed into a 10-foot deep septic tank – a concrete chamber where the untreated filth of toilets collect – to clear a blockage. He followed three others down into the stinking pit. Two of them did not come out alive and Sher Singh has been an invalid since then. “As the others went in, they just sat there inside with their back against the pit wall… The same with me, we lost consciousness. Later they said it could have been methane gas.” …