The Indian Railways need to buy 3,350 truckloads of cow dung at Rs 42 crore in 2018 to “recharge”–add bacteria to activate degradation–leaky, malfunctioning ‘bio-toilets’ that it has fitted on 44.8% of trains and hopes to expand to all trains by 2018, according to IndiaSpend projections of data released by the national auditor to Parliament.

Bio-toilets are small-scale sewage-treatment systems beneath the toilet seat: Bacteria in a compost chamber digest human excreta, leaving behind water and methane. That’s how they were supposed to ...