This research looks at the negotiations and struggles around the proposed new water policies in Peru, with a focus on how peasant and indigenous water users try to defend their water security. Framed in neo-liberal terms, and developed with the objective to increase the efficiency of water use in view of looming water crises, the proposed policies offer few possibilities for existing indigenous irrigation communities to claim water rights. This is increasingly recognized, and has resulted in the inclusion of special decrees for the recognition of indigenous water rights in new policies. Suggestions to base claims to water on ethnicity have also come from activists and scholars in Peru, and is a widely adopted strategy across the Andes. This research intends to explore the implications of thus linking ethnicity to water allocation, in view of critically questioning ethnicty as a basis for water claims. The main hypothesis that guides this exploration is that ethnicity, and especially in its neo-liberal definition, provides a tricky basis for water security. This is so because the precise meaning of ethnicity is not straightforward, and because operationalization of the `ethnic clause¿ is difficult. Claiming water upon acceptance of ethnic status implies agreeing to be treated as `the other¿, as that which cannot be contained in normal laws or policies. The linkages between ethnicity and water uses or water needs are also not directly causal, which is why implications for water efficiency and sustainability are not clear. The research proposes to qualify, document and analyze how male and female water users themselves employ notions of ethnic identity and ethnicity in their day-to-day water use and distribution practices, and in their negotiations for water with competitors and the government. Different strategic uses and meanings of ethnicity and ethnic identity are contrasted and compared to its meanings in official policy documents. Gender will be used both as a focus, as well as an entry-point to start understanding processes of identity formation and identification in water. The research links water management at the level of irrigators¿communities to water management at higher hydrological levels: watersheds and river basins and is innovative in its lonking of physical and technical questions to social, political and legal questions.