This article deals with an important aspect of public health policy in the two leading industrializing countries of Europe. Both had a substantial number of large towns in this period, despite the fact that German industrialization had only just begun in 1859. It is a companion piece to a comparative study of vaccination policy published in 1998, and is intended to be complemented by a study of the impact of bacteriology on public health. It is for that reason that little attention is paid to bacteriology here. The first study dealt with the concept of medical police; it was about modes of compulsion. This one is about the provision of a sanitary infrastructure of central water supply, sewerage and sewage treatment. It deals not so much with the ordering of people as with the making of things.