Fly ash disposal through high concentration ash disposal system (HCSD) is followed in many coal based thermal power plants in India. Efforts to reduce the dilution of the slurry will result in energy conservation as well as water conservation. The latter is even more important to overcome the problem of excess water consumption. To evaluate the effectiveness of the slurry disposal system, it is important to measure the concentration of ash in the slurry being transported through high concentration slurry disposal system (HCSD). Attempts have been made to obtain the exact slurry concentration and water retention capacity of fly ash through laboratory experiments. It is observed that the density of slurry varies from 1.17 to 1.60 for different concentration of the slurry and water holding capacity of ash increases with the increase in ash concentration. Maximum possible water recovery is observed between 57-58% of total water used for the slurry concentration.