Optimal design of a water distribution network is formulated as a two-
stage decomposition model. The master (outer) problem is nonsmooth and
nonconvex, while the inner problem is linear. A semi-infinite linear
dual problem is presented, and an equivalent finite linear problem is
developed. The overall design problem is solved globally by a branch a
nd bound algorithm, using nonsmooth optimization and duality theory. T
he algorithm stops with a solution and a global bound, such that the d
ifference between this bound and the true global optimum is within a p
rescribed tolerance. The algorithm has been programmed and applied to
a number of examples from the literature. The results demonstrate its
superiority over previous methods.