Is there an official municipal management ranking?

Yes: the planning secretariat (SEGEPLAN) publishes the Municipal Management Ranking (RGM); the latest edition is 2020-2021, covering 340 municipalities with 6 indices and 55 indicators,… plus an interactive viewer with data by municipality and department. SEGEPLAN also publishes the Municipal Development and Land-Use Plans (PDM-OT) for each municipality as PDFs, with land use and service gaps - a likely source for municipal water capacity outside the capital.