Plumbing 101
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If you're lucky, you rarely need to worry about your plumbing. Your toilet flushes and your sink drains smoothly; you have plenty of hot water and your shower has good water pressure. But luck doesn't last forever. Many problems can occur in this system. Pipes can break, drains can plug, and valves can leak. When trouble arises, it's helpful if you know how the system works. This knowledge can help you save money, prevent damage to your home and keep your family safe.

The basics of plumbing are easy to understand. There are two separate subsystems in the plumbing system of your home, one that brings water in and one that takes wastewater back out. Water enters you house through a pressurized water line. The pressure of the water coming in allows it to move around corners and even upstairs. After being split into hot and cold water lines, the water supply runs to each fixture in your home.
The second subsystem in your home is for drainage. Once used, fresh water becomes wastewater, and it enters the drain-waste-vent (DWV) system. Gravity now takes over, pulling the wastewater down a series of sloped, ever larger pipes where it will flow to a sewage treatment facility or septic tank.

Water volume is vital to plumbing. All fixtures operate within a range of water volume. The plumber must ensure that each fixture, from the faucet to the laundry hose receives the correct amount of water volume. Plumbers rely on the internal diameter of the water pipes to control water volume. Surprisingly water pressure and water volume are not the same. The pressure remains the same, but the volume may change due to the variations in pipe size.

Gravity is another crucial part of a plumbing system. Plumbers use gravity to move the drainage and waste removal of the system. Drainage leaves your house because the pipes all pitch, or angle downward. Your system must also be properly vented in order to release air pressure, or it will lose its flow.

When designing or repairing a system, a plumber’s job is often dictated by local, state and federal codes. These codes will specify the internal diameter of pipe that must be used for a particular plumbing section or function. An example of this would be, pipe of increasingly smaller diameter is called for as the supply pipes branch out from the water main that enters the house. This is because the water coming out of the main is under too much water pressure for an individual fixture (sink, toilet, etc.) to handle. This decreasing drop in pressure as water moves away from the main to primary supply lines then to secondary supply lines, ensures that each appliance receives the correct amount of pressure and volume of water.
As mentioned previously, a plumbing system must be vented. Vents are the pipes you see sticking out of the roof of your house. These allow air to enter the drainpipes. Without this air supply coming in, wastewater would not flow out properly and the water in the traps (under a sink) would need to be siphoned away.

Traps are another important component of the drainage system. Every sink will have one under it; it is the S-shape section of pipe under the drain. Water that flows from the basin of the sink goes through this trap and out through the drainpipe. Enough water remains behind to form a seal that prevents sewer gas from backing up into your house. Every fixture must have a trap. This area under your sink is where you will often get a build-up of hair and grease and need to break up the clog or call a plumber to remove the clog.

In a plumbing emergency, it's vital that you quickly close the main shutoff valve. Every homeowner should be aware of is where the emergency shut-off valves are located in their homes. Otherwise, when a pipe bursts, it can flood your house in no time. If the emergency is confined to a sink, tub, or toilet, however, you may not want to turn off your entire water supply. Therefore, most fixtures should have individual stop valves.
The most important valve in your house is the whole house shut-off valve. This is usually located near the foundation, either inside or outside your home, often in the basement or garage. If you ever have problems with this valve you should have it replaced immediately. The whole house hot-water turn-off is usually located on top of the water heater. Other fixtures in your home will have individual shut-off valves, such as toilets, sinks, dishwashers, and clothes washers.

Knowing some basics about the plumbing in your home can help save time and money when you encounter a problem. This knowledge can also save your home from serious damage if you ever have a pipe burst or a leaky fixture. And not least of the reasons, knowing your plumbing system will help you and your family stay safe if you ever have a plumbing emergency.

Sources:      www.howstuffworks.com
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