Social justice and water refers to fairness of access to water resources and equality of burden from poor water quality and water hazards. This chapter considers briefly the origins and definition of social justice, and ways in which social justice and water interact. Global scale water justice is considered mainly in respect of disease and the lack of progress towards effective provision of water and sanitation. A detailed case study of the links between water debt and deprivation in the UK is then examined, concluding with a consideration of the options available to resolve water debt issues whilst respecting social justice. We conclude with a consideration of the future constraints on water resources in the light of the latest UK climate projections, and recognise that difficult choices might be encountered in which social justice for people might have to have priority over environmental justice for river and land habitats.