This study assesses the different water supply options available to people in Vietnam's Mekong Delta (VMD). It ascertains which source is the cleanest and most sustainable, and then sees whether people can be encouraged to switch to this source. The study finds that there are three main sources of water in the VMD - rainwater, river water and groundwater. Of the three options, groundwater represents the best alternative both in terms of its popularity and its cleanliness. The best method to supply this resource is through groundwater supply units or GSUs. GSUs extract water from a geological level where it is less polluted and, because users have to pay a fee for the water they use, they also encourage water conservation. Calculations of potential supply and demand show that GSUs would be a sustainable option. The study concludes that people would be willing to switch to this popular option and recommends that the GSU program should be widely promoted by government.