In this study, a nonlinear programming approach using the successive q
uadratic programming optimization technique is developed for the optim
al design of a pipeline network for water supply systems. The proposed
method eliminates the equality constraints describing the hydraulics
by a suitable choice of dependent and independent variables. The depen
dent variables are chosen based on graph theoretic decomposition of th
e network structure. This makes it possible to compute analytically th
e reduced constraints, objective function gradients, and reduced Hessi
an in a very efficient manner. This method of decomposition ensures th
at the nodal and loop balances are exactly satisfied and is robust for
any initial starting point, able to handle incorrect initial dow dire
ctions. The method gives solutions comparable to the previous optimal
solutions for the design of new as well as expansion of existing water
distribution networks.