The problem with uninterrupted access to drinking water is an important issue in the everyday life of the inhabitants of medieval and modern cities. It is especially significant in terms of preventing epidemics that have often plagued urban centers, where the level of hygiene left much to be desired. The oldest preserved Frombork city ledger from 1630-1645 draws attention to six pages with a list of six city wells with personal details of people using them for a fee in 1639. This list, rarely found in city documents, illustrates the activities of the Frombork authorities in the second quarter of the 17th century, during the difficult times of the Swedish invasion and the war of 1626-1635 that echoed through the city and the whole of Warmia, and even after the end of the wartime turmoil. This source is an illustration of the degree of municipal self-reliance and the responsible actions of Frombork's authorities and its citizens for the common good: caring for the improvement of hygiene and health of the inhabitants.