Measuring Leptonic CP Violation with a Water Cerenkov

In this talk, we present the physics case for a megaton Water Cerenkov detector in addressing some of the still pending questions in neutrino oscillations physics, particularly the measurement of leptonic CP violation. We compare different future beams that could profit from a water detector and analyse, for the case $\theta_{13} \approx 3^\circ$ (the limit that can be reached by under-construction experiments), the signal-to-background rate for a $\beta$-beam setup with the radioactive ions accelerated to $\gamma = 350$.