Pure Ho2Ti2O7 exhibits spin ice beahviour. Studies of doped spin ice, replacing Ho with non-magnetic Y, suggest that the spin ice state is present even when the amount of doping is as high as 50%. The retention of the characteristics of a spin ice at such high Y doping levels is rather puzzling. One possible explanation is that for higher levels of Y doping, phase segregation begins to occur and there are regions of the sample which are richer and poorer in Ho. We propose to use muSR techniques to investigate this possibility. We will study five samples of Ho2-xYxTi2O7 with x = 0.0, 0.3, 1.0, 1.3, and 2.0. To ensure only the highest quality materials are used the samples will all be single crystals. The pure spin ice x = 0.0 and non-magnetic x = 2.0 will be used as reference materials.The three intermediate compositions will then be studied to ssearch for evidence of phase segregation.