This note on water security presents a synopsis of the water security situation for the Greater Horn of Africa (GHoA). It complements the Country Water Sector Profiles (CWSP) of seven nations of the GHoA, including Eritrea, Ethiopia, Kenya, Somalia, South Sudan, Sudan, and Uganda. The note examines the dimensions through which the risks and impacts will be felt most strongly in the future. These include water quantity; water quality; and water accessibility. It is prepared to inform the Bank engagement in strengthening investments in enhancing water security.