The paper presents the development and implementation of a geo-spatial model for mapping populations' access to specified types of water and sanitation services in Nigeria. The analysis uses geo-located, population-representative data from the National Water and Sanitation Survey 2015, along with relevant geo-spatial covariates. The model generates predictions for levels of access to seven indicators of water and sanitation services across Nigeria at a resolution of 1×1 square kilometers. The predictions promise to hone the targeting of policies meant to improve access to basic services in various regions of the country.