💧 Gravity Water Network: Hardy Cross Loop Balancing and Pressure Heads (2D)

A reservoir feeds four districts through six pipes that form two loops. Set the demand of every district, the pipe sizes, the roughness and the reservoir level and watch the Hardy Cross iteration correct the loop flows step by step until the head losses around each loop cancel. Flows, pressure heads and the lowest pressure against demand are plotted, and continuity, loop energy, an independent Newton solver and the power balance are checked, with four in-page numerical checks.