Every house in a developed country, no matter where they are or the size, is going to have basic plumbing. The plumbing may seem like the most complex part of a house, but if you understand how the plumbing system works, you will realize how straightforward plumbing can be. Besides, understanding a basic plumbing system will help you in the future when you need to describe an issue to a professional plumber. 


Relevant: Beginner’s Guide to Plumbing Codes

So, let’s not waste any time. Here is the gist of how your home plumbing system works: 


The Main Parts

When you look at a diagram of a typical plumbing setup, you will see that there are only two sections: the half of the system that brings water in (known as the water supply), and the other part of the plumbing system that expels waste water from your home (known as the drain-waste system). That’s it. 


Of course, it can be a bit more complicated in design than a simple in-and-out. We will explain both parts of the plumbing system in more detail. 


The Water Supply System

As the name suggests, the water supply is the intake of water into the household. Water circulates from the main valve. Depending on the source of the water—city or well—the main valve switch is either located in front of the house, buried under the street, or somewhere close by. The water supply is pressurized so that it can reach every section of your house, no matter how many floors it must ascend. 


Those with city-sourced water have a main pipe, a large line that runs parallel to the street. For those with wells, there will be a pump in your home that pressurizes the water when needed. 


Beside the water meter (or somewhere close), there is a shutoff valve for the whole system in your house. In the event that you have a burst pipe or some other issue, you can use the shutoff valve to shut down the system and prevent more water for entering the pipelines. 


Another section of the water supply system is the line that leads to the water heater. Some houses, apartments, and condos (typically newer construction) use something called a tankless water heater, since they are much more energy efficient. However, both a traditional tank heat and tankless heater need that supply line. 


The main concern with the water supply system is cleaning and having sufficient pressure to reach every water fixture. You need the water supply system to function properly. Otherwise, you might have an issue with taking a shower or flushing a toilet. 


The Drain-Waste System 

Once you have used water, it goes down a drain. At this point, the water is no longer considered fresh. Now, it is waste, and it must be redirected away from your home. Gravity takes over now. 


You will see that drain-waste pipes are angled down to let gravity do its job. Because of this, the drain-waste system is much more complicated than the water supply system. There are added features, such as traps, vents, and other additions to make the drain-waste pipes much more effective. For example, there is something called the P-trap, which captures solid items that fell down drains. There are also switchbacks and vents that stop noxious sewage fumes from rising back into your home. 


You might also note the vent atop your roof. That, too, is part of the drain-waste system. 


Drain-waste piping is much wider than water supply pipes. That is because the drain-waste system is carrying more than water through the lines. Larger pipes prevent blockages from forming. 


Cold vs. Hot Water Supply

Now, where does the hot water from your shower come from? The water that flows into your household is usually cold. Whenever a sink is turned on or someone is taking a shower, cold water rushes into the supply line, using a centralized line that moves between the floors of your home. If you need hot water, the cold water is fed into the hot water heater—or a reserve is drawn—and is shuttled up short, straight piping. 


The reason hot water only travels through short pipe connections is because of heat transference and loss. If it used the same routes as cold water, you would have to wait twice as long for warm water. 


Identifying Issues Within Your Home’s Plumbing System

There will come a time when the water in your home doesn’t flow properly. This is typically caused by a blocked pipe or similar issue. In that case, you should consider discussing the issue with a professional plumber, since they will have the correct tools. However, depending on where the problem is occurring and when, you may be able to identify the issue more quickly. 


Here are some common problems to consider: 


  • Cracks in the foundation
  • Sewage blockage
  • Septic waste in the yard
  • Insect and rodent problems 
  • Mold 
  • Slow or gurgling drains


Wrapping Up

You should now know that there are two main parts to every plumbing system: the water supply and the drain-waste system. Understanding the functions of these two systems, as well as the common issues involved, can help you describe problems more accurately to the plumber. You should also be able to take better care of your plumbing system now that you see how everything operates.