Tariff modelling is not something water operators do often. However tariff modeling is crucial for water utilities because it provides a framework for setting fair, reasonable, and sustainable water prices that balance the utility's need for revenue with the affordability for consumers. Effective tariff models ensure cost recovery, encourage efficient water use, and promote equitable access to water services. UN-Habitat promotes fair water tariffs as part of its broader water and sanitation programs, advocating for policies that ensure access to affordable and safe water for all, especially low-income households. This includes implementing tiered or lifeline tariffs, where the initial block of water is priced lower to ensure basic needs are met, while higher consumption is charged at a progressively higher rate. This training event will equip participants with ability to use a simple xlxs tool to compare the impact of customisable block water tariffs. The tool was developed in the frame of the WOP between Hamburg and eThekwini Participants need only a basic level understanding of Mircorosft Excel and access to a laptop with a recent version of Excel to participate.