There are few sectors where ‘getting things done sustainably’ is as important as it is for the water sector. Using detailed case studies from Africa, Asia, Europe and Latin America, the authors assess the role and potential of social entrepreneurship for the sustainable use of water. The chapter "Musketeering for drinking water" focuses on Viva con Agua de Sankt Pauli, a multi-faceted non-profit organization that aims at improving access to water and sanitation wherever this is severely limited or non-existent. Their motto ‘Water for all and all for water’ borrows from Dumas’s musketeers and captures well the mission and spirit: access to clean water and sanitation shall be granted to everyone and everyone shall engage in this mission. The chapter describes and evaluates their innovativeness, their approach to change and scaling as well as their sustainability contribution and legitimacy.