Background: Ensuring access to improved water and sanitation remains a public health challenge in Ethiopia. Exploring geographic variation and inequalities in access to improved drinking-water supply and sanitation will help track progress towards to meet sustainable development goals of water and sanitation.

Objective: To explore geographical variations and inequalities in access to improved drinking water and sanitation in Ethiopia.

Methods: A total of 16, 650 households from 643 enumeration areas of the recent Ethiopian Demographic and Health Survey 2016 data were extracted and included in the analysis. World Health Organization recommended definitions were used to measure the indicator of basic services of improved drinking water and sanitation at enumeration areas. Satscan spatial analysis was done using cluster of enumeration areas as center for exploring geographical variations of improved water and sanitation. Absolute and relative inequalities were used to quantify subnational regional inequalities in access to improved drinking water and sanitation.

Results: Access to improved drinking water and sanitation in Ethiopia was 49.6% (95% CI: 48.4-50.7) and 6.3% (5.8-6.8), respectively, with large variations between and within regions. Access to improved drinking water ranged from 28.5% in Somali region to 95.3% in Addis Ababa and access to improved sanitation ranged from 1.7% in Amhara Region to 24% in Dire Dawa. Households lacking access to improved water and sanitation were clustered in northwestern (Amhara Region) and southern (South Nation and Nationalities and People Region) parts of Ethiopia. Most enumeration areas had very low level access to improved drinking water and/or sanitation.

Conclusions: There are geographical variations and inequalities in access to improved drinking water and sanitation in Ethiopia. Monitoring geographical variations and inequalities using spatial analysis and inequality indicators serves to identify underserved population which is useful for developing approaches to improve inequalities and achieve the 2030 Agenda for Sustainable Development.