John,
Welcome to the fun world of hydraulic modeling! It's great for puzzle solver-minds; never ending. If you are using ArcMap or ArcGIS Pro, for this type of analysis, there are a handful of modeling software's available in the water modeling industry that operate within Esri software. One of our Esri partners, Innovyze, along with one of Esri's solution engineers, Jason Channin, gave a good presentation on a hydraulic modeling tool working inside ArcGIS here. Outside of modeling software itself, there is quite a lot that goes on in a water network. You may find this video useful - it covers how water systems function (by one of my favorite youtuber channels, Practical Engineering). Feel free to reply with what you are trying to solve/answer, and the Geonet community here will be glad to help you along the journey.
Respectfully,
Martin