Service level is the quality or standard of service, measured by criteria set by national standards and/or the norms for Sustainable Development Goal 6. The criteria for water include quantity, quality, reliability and accessibility; for sanitation, they are accessibility, use, reliability and environmental protection. [Source: Huston, A. & Moriarty, P.B., 2018. Understanding the WASH system and its building blocks : building strong WASH systems for the SDGs. (IRC WASH systems series) The Hague, the Netherlands: IRC. P. 5-6].