Kurban Sitterley enhanced the costing module in the watertap-org/watertap repository by improving both documentation and currency unit handling. Using Python and Sphinx, Kurban standardized documentation for costing methods, corrected formatting and typos, and added references to clarify guidance for users. They also updated the electricity_cost unit from a fixed USD value to a flexible base currency, ensuring consistency across modeling and test workflows. This required careful adjustment of test cases and unit conversion logic to maintain reliability. The work improved cost modeling clarity, reduced error risk, and supported easier onboarding for engineers, reflecting a thoughtful, detail-oriented engineering approach.