Abstract: A sectional modular system for making sanitary plumbing fixtures includes: one or more base components which are designed to be placed in a wall in a built-in position and to be put in fluid communication with one another and/or with a water distribution line; at least one removable component such as a mixer, associated in fluid communication with the base component and a support and centering structure for supporting two or more base components; advantageously, each base component includes a body divided into a first water chamber and at least four additional water chambers.