Malwathu Oya Basin which covers 2350km2 located in Anuradhapura district is considerably populated and the safety and the available quantity of water is crucial for the people. Water samples were collected from selected locations during South-
West monsoon period, Second Inter monsoon period and North-East monsoon period from September 2016 to March 2017. The samples were analysed for pH,
turbidity, conductivity, fluoride, chloride, magnesium and calcium as basic drinking water quality parameters. Only the shallow regolith aquifers are considered for the
study. The groundwater quality variation of the area shows a considerable variation from dry season to rainy season in general water quality of the area, and is in acceptable limit for most of the basic parameters. With the seasonal changes Fluoride and Chloride content is higher than permissible limits in some areas
