Bat guano is an old faecal matter of bat. The sugar factory effluent has the characteristics of hardness due to the presence of Ca++ and Mg++ . In the present study an attempt has been made to employ the Bat guano to reduce the hardness of the reclaimed water from sugar factory. There was a significant decrease of hardness against controls. There were 10.47, 14.82, 22.63 and 31.88% reduction at the interval of 10, 20, 30, 40 days in the water after application of Bat guano. The results are discussed with hardness pollution reduction. The present investigation indicates that bat guano used for degradation of water pollutants and bioremediation of aquatic ecosystem and also for waste water treatments.