This document provides an introduction to building services related to plumbing. It defines building services as everything inside a building that makes it safe and comfortable, including lighting, HVAC, plumbing, and other utilities. The document then discusses the specific building service of plumbing. It covers water supply and sanitation, describing different water sources like surface water, groundwater, and desalination. It also discusses wells, springs, and infiltration galleries for accessing groundwater. The intent of the subject is appreciating the design and layout of water supply, plumbing, drainage, and sanitation in simple buildings.