P Sheets (plumbing drawings): These depict where pipes, water tanks, and plumbing fittings are located. Vents in plumbing systems allow sewage gases to safely leave the building by cutting through the roof. E Sheets (electrical drawings): These drawings provide precise information on the electrical layout of a structure. They show the location of circuit breakers, switches, outlets, and other electrical components. Plumbing fixtures include toilets, sinks, bathtubs, showers, and dishwashers. When you think about it, these are the only things that need to be located near the plumbing in a house. The other major appliances such as heaters, air conditioners, and water heaters don't have their own specific fixture type. They're called "appliances" because they serve a functional role within the home, but they aren't fine or drinking water faucets. They're just appliances. Toilets, sinks, and baths all use Fixtures. Showers and Jacuzzis use Accessories. Dishes used to be considered a separate category until recently when they were included under Sinks. But even though they use the same fixture type as a sink, they function more like a toilet. So, plumbing drawings will usually show the locations of toilets, sinks, and baths, along with their dimensions. They'll also show the location of water supply and drain lines that feed into or out of these plumbing elements.