Tamilnadu is deficit in Water Resources. It is a major fresh water lake in the cuddalore district of tamilnadu. It is located almost 7 kilometers (4.3 mi) from Alapakkam,The rainfall is seasonal and often erratic in timing and geographical distribution, resulting in frequent droughts and occasional floods. To mitigate the adverse effects, serious attention is required to rehabilitate the existing irrigation structures, canal systems, anicuts and tanks to make them functionally more effective, conserve and utilize the water for optimum use.This paper deals with an assessment of water quality parameters of Perumal eri(lake) situated at Alapakkam in Cuddalore district.Samples have collected at five different locations in Perumal eri during pre-monsoon period.Then laboratory analysis has done and the results are compared with BIS and WHO drinking water standards.Then by using “Inverse Distance Weighting”(IDW) method geostatistical analysis has done.Based on the results obtained mapping contaminants in lake has done by using ArcGIS software.According to the results suitable solution will be given to treat the water in the lake.