Rajendra Singh is an Indian water conservationist and environmentalist from Alwar district, Rajasthan in India. Also known as "waterman of India", he won the Magsaysay Award in 2001 and Stockholm Water Prize in 2015. He runs an NGO called 'Tarun Bharat Sangh' (TBS), which was founded in 1975. The NGO based in village hori-Bhikampura in Thanagazi tehsil, near Sariska Tiger Reserve, has been instrumental in fighting the slow bureaucracy, mining lobby and has helped villagers take charge of water management in their semi-arid area as it lies close to Thar Desert, through the use of johad, rainwater storage tanks, check dams and other time-tested as well as path-breaking techniques. Starting from a single village in 1985, over the years TBS helped build over 8,600 johads and other water conservation structures to collect rainwater for the dry seasons, has brought water back to over 1,000 villages and revived five rivers in Rajasthan, Arvari, Ruparel, Sarsa, Bhagani and Jahajwali. He is one of the members of the National Ganga River Basin Authority (NGRBA) which was set up in 2009, by the Government of India as an empowered planning, financing, monitoring and coordinating authority for the Ganges (Ganga), in exercise of the powers conferred under the Environment (Protection) Act, 1986. In the UK he is a founder member of an NGO called the Flow Partnership which aims to counter the negative effects of soil erosion and flooding.

The Ramon Magsaysay Award is an annual award established to perpetuate former Philippine President Ramon Magsaysay's example of integrity in governance, courageous service to the people, and pragmatic idealism within a democratic society. The prize was established in April 1957 by the trustees of the Rockefeller Brothers Fund based in New York City with the concurrence of the Philippine government. It is often called the "Nobel Prize of Asia".