The rivers and streams that ran through late medieval towns and cities were a source of ill health and sustenance alike. Contemporaries recognized that there was a connection between polluted water and disease, which could be understood in terms of both disease transmission via the corrupt air that emanated from waste-filled or stagnant water, and direct poisoning through drinking such water. At the same time, the ready availability of water for drinking, washing, and industrial processes such as dyeing cloth, as well as for waste disposal, was essential to the wellbeing and prosperity of the urban population. Water sources also supplied fish, a key component of the diet of medieval people, especially in the maritime region of Normandy in north-western France. Furthermore, bathing in certain waters was considered to alleviate the symptoms of illnesses such as leprosy, while also contributing significantly to spiritual health.

This chapter investigates how the regulation of water sources formed part of public health provision in the towns and cities of fifteenth- and early sixteenth-century Normandy. As we shall see, however, the longevity of certain ideas and practices concerning water and health in Normandy is apparent from evidence dating back far earlier, to the twelfth century at least. The following analysis encompasses not only rivers and streams, but also piped water systems, wells, sewers, ponds, ditches, and marshy land, as well as the sea. It takes into account late medieval assumptions about health and disease, especially regarding the transmission of sickness via corrupt air and other types of environmental pollution.