In the second half of the nineteenth century, for Paris, as indeed for all major European cities, the supply of drinking water was a matter of great concern. Two factors combined to make this so: Paris’ rapidly growing population and the manifestly worsening quality of river water. ‘During the last twenty years, the deterioration and corruption of watercourses has progressed rapidly. A large number of rivers, hitherto very pure, have become foul spillways. All watercourses in the department of Seine have successively become infected’, Gérardin wrote.1 Everywhere, the deterioration of flowing water, equally apparent in London, Brussels or Berlin, had the same cause: sewers pouring industrial and domestic waste water into it. This situation drew the attention of governments and, in France in the 1860s, gave rise to lively discussions at the Académie des Sciences and the Académie de Médecine. It made sense ‘to take note of the composition of Seine water upstream and downstream of Paris, the impairments that it suffers on passing through the city and the suburban boroughs, [. . .] and of the effect of these impairments on the salubrity of water distributed to the populace’.2 The initial problem was the quality of drinking water supplied to the inhabitants of Paris: was it adequate to meet demand without causing infectious diseases among a population as yet rather defenceless against them, some 20 years before the revolution brought about by Pasteur in the 1880s? But the debate went beyond the issue of public health: it was occasioned by the growing capacity of Paris’ water supply and sewerage systems. Although they stood as symbols of modernity and of the city’s improved hygiene, they were not without negative aspects, as evidenced by the marked worsening of water quality in the Seine since the 1840s. The first part of this paper will recall the

1 A.C. Gérardin, Rapport sur l’altération, la corruption et l’assainissement des rivières (Imp. Nationale, 1874), 2. All quotes from French sources have been translated by the author. See also M.G. Grimaud, ‘Des rivières et de leurs rapports avec l’industrie et l’hygiène des populations’, Comptes-rendus de l’Académie des Sciences, 58, 1864, 955-9.