Urban water distribution networks do not always supply water continuously or reliably. Hundreds of millions of people in cities worldwide regularly experience intermittent water supply, a condition that degrades distribution system components, compromises water quality, and limits water availability. I will introduce this phenomenon and our implementation of an efficient computational model of transient, transition flow through a network of pipes. I will show several optimization examples using this model, including mitigating pipe damage and estimating unknown parameters. I also discuss how simple fluid mechanics principles may help identify flow regimes where this model is most useful.