Part One
How the Water Moves
Every house runs on two systems that never touch: one brings clean water in under pressure, the other lets used water fall away by gravity. This first part of the book is a walk through both, from the main under the street to the vent on the roof. It explains why a drain must slope, why a bend full of water keeps the sewer out of your bathroom, and why a sink gurgles. It shows you how to find the valve that stops everything, and how to measure the pressure behind it. It also draws a line, early and plainly, between the work that is yours and the work that belongs to a licensed trade. Nothing here needs a toolbox beyond a flashlight, a pencil and a gauge. Read these chapters on a quiet day, and the later ones will come easier when the day is not quiet.