Plumbing in general follows the basic laws of nature – gravity, pressure, and water seeking its own level. Knowing this can help you understand the mysteries of your home or businesses plumbing system.
Plumbing systems are composed of two separate subsystems. One system brings freshwater in, and the other takes waste water out. The water that comes in is under pressure, enough pressure to travel upstairs, around corners, or wherever else it’s needed. As water comes in, it passes through a water meter (generally speaking) that registers the amount of water used. Typically there is a main water shutoff close by. In a plumbing emergency, it is important to quickly close the main shutoff valve. If the emergency is confined to a single fixture, you may not need to turn off the entire water supply if the fixture has an individual stop valve.
Water from the main supply is immediately ready for cold water needs. The hot water supply, however, requires a further step. One pipe from the main supply carries water to the water heater. From the heater, a hot water line carries the heated water to all fixtures, outlets and appliances that require hot water. A thermostat on the heater maintains the temperature setting typically between 140 and 160 degrees F.
Drainage Systems: Drainage systems do not depend on pressure as water supply systems do. Instead the basic operating principle is atmospheric pressure (the pressure of the air and atmosphere surrounding us also known as barometric pressure), and in practical terms zero pressure. Waste matter leaves your house or business because the drainage pipes all angle downward. Gravity pulls the waste along. The sewer line continues this downward flow to a sewage treatment facility or a septic tank.
While this system sounds simple, there’ s more to it including vents, traps, and clean outs. The vents sticking up from the roof allow air to enter the drainpipes. If there were no air coming in from the vents, waste water would not flow out properly, and the water in the traps would need to be siphoned away.
Traps are also vital components of the drainage system. A trap can be seen under every sink. It is the curved or S-shaped section of pipe under a drain. Water flows from the basin with enough force to go through the trap and out through the drainpipe, but enough water stays in the trap afterward to form a seal that prevents sewer gas from backing up into the room. There must be water in traps under sinks and bathtubs at all times. If the water gets sucked out by poor venting or improperly sized drains this will allow sewer gas to come in. Every fixture that drains must have a trap. Toilets are self-trapped and don’t require an additional trap at the drain. Because grease and hair are frequently the causes of drain clogs, traps often have clean-out plugs that give easier access to remove or break up any blockage.
The drainage system is usually referred to as the DWV: it includes three main components: the drain-waste-vent system, and all components must be in good working order for the system to function properly.
Supply and Drainage Subsystems: The supply and drainage subsystems are two distinct operations as already mentioned. However there are bridges between the two and the bridges are what make the plumbing system so nice to have and use. In plumbing jargon, any bridge between the supply and drainage systems is a fixture (such as a sink that handle water coming in and water going out).
Toilets, sinks, and tubs are fixtures. So is a washing machine. All devices that draw freshwater and discharge waste water are fixtures, and all are designed to keep the supply and drainage systems strictly segregated. Some fixtures have individual shutoff valves so that the main shutoff doesn’t need to be turned off for repairs or in case of emergency.
Publications International, Ltd.