Stockholm – RELX Group, a world-leading provider of professional information solutions, today announced the winners of the 2015 RELX Group Environmental Challenge, which supports innovative solutions to improve sustainable access to safe water and sanitation. The $50,000 first and $25,000 second prize winners were recognised during World Water Week in Stockholm, a unique annual event bringing together water researchers, policymakers, journalists, companies and non-profits to address the key water challenges of the 21st century.