Groundwater is one of the most important sources of fresh-water for the people living in the Vietnamese Mekong Delta. Particularly, in the coastal provinces of the Mekong Delta, local people essentially rely on groundwater for domestic uses and agriculture. The quality of groundwater is hence a matter of great concern. Mapping groundwater quality over an area is needed for a better planning of ground water quality monitoring stations and efficient remedy for possible pollutions. Spatial interpolation method is often used for mapping ground water quality over an area using data from discrete monitoring wells. Different interpolation methods can result in groundwater quality maps of different accuracies. This research studies the effects of inverse distance weighted interpolation and kriging on the accuracy of mapping ground water quality in Can Tho city, Viet Nam. The accuracy of mapping is quantified by cross-validation using data of Arsenic, COD and Chloride from 34 monitoring wells across Can Tho city. The information about the accuracy of these groundwater quality maps will help the authorities optimize groundwater quality monitoring and sustainable management of groundwater resource.