This working paper provides a framework for data analysis of life-cycle costs. This paper explores costs at three levels including: 1) total aggregate services across the whole population; 2) within different service levels; and 3) between technology types. Service level is defined as a collection of indicators of service provision, together with acceptable ranges for these indicators. The ladder is a useful metaphor for the idea that a progression should take place from lower to higher levels of service. This structure helps data analysis in different countries, related not only to the technologies being used, but also to the terms of the domestic water services being received. This second edition reflects the experiences of applying this methodology in Burkina Faso, Ghana, Mozambique and India (Andhra Pradesh).