A Series of ILP models for the optimization of water distribution networks

The design of rural drinking water schemes consists of optimization of several network components like pipes, tanks, pumps and valves. The sizing and configuration of these network configurations need to be such that the water requirements are met while at the same time being cost efficient so as to be within government norms. We developed the JalTantra system to design such water distribution networks. The Integer Linear Program (ILP) model used in JalTantra and described in our previous work solved the problem optimally, but took a significant amount of time for larger networks—an hour for a network with 100 nodes. In this current work, we describe a series of three improvements of the model. We prove that these improvements result in tighter models, i.e. the set of points of linear relaxation is strictly smaller than the linear relaxation for the initial model. We test the series of three improved models along with the initial model over eight networks of various sizes and show a distinct improvement in performance. The 100-node network now takes only 49 s to solve. These changes have been implemented in JalTantra, resulting in a system that can solve the optimization of real world rural drinking water networks in a matter of seconds. The JalTantra system is free for use, and is available at https://www.cse.iitb.ac.in/jaltantra/.