Biodigester Technology of DRDO has provided a decent on-board solution to the problem of unhygienic discharge of human excreta on railway tracks. Biodigesters are not only cost effective practical solution of on-board sanitation but are also space saving and maintenance free. They work efficiently against all temperature variables, fluctuating number of commuters, and require less water and no electricity for their functioning. Indian Railways has already installed thousands of biodigesters and has decided to fit all its passenger coaches with biodigester based biotoilets. This book is an endeavour to compile the information about the Biodigester Technology developed for Indian Railways. The book has been arranged into seven chapters covering aspects on the impact of human waste on sanitation and diseases, efforts of Indian Railways for onboard disposal of human waste and the technological developments of biodigester during its adoption in Indian Railways, and finally future R&D prospects for improvement in the Biodigester Technology. It is believed that the book will create awareness about sanitation in society and facilitate the policy makers to adopt this technology for safe and scientific disposal of human waste in rural and urban societies in addition to Indian Railways.