How Plumbing Works in a Home
Have you ever wondered how water makes its way up to your second-floor shower or what happens to the leftover toothpaste making its way down the drain? While it can seem like a very mysterious system hiding behind those walls it's actually a careful organization of piping working together in a rather straightforward way.

First, where does the water come from?
Your plumbing system wouldn't do any good without the key ingredient, water. But where exactly is that water coming from? There are two main water sources from which water is pushed into your home:
- Water found directly on your property (usually a well)
- Your city or county's water system
It All Comes Down to Two Systems
Water In and Water Out
All of the plumbing in your home is broken down into two subsystems. You may even be able to guess what they are. One brings fresh water into the house via pressure and one removes the wastewater via gravity. These two systems are known as the water supply pipes and the drain-waste-vent system.
Water Supply Pipes
Water makes its way to your house through this pipe which is the largest pipe in the supply network (usually about 1 inch wide) and is pulled from whichever water source your home uses (well or city). This water is under high pressure to make sure it can get to every part of the house.
If you are on city water, this pressure is created by pumping stations. If your water is coming from a well, there is a well pump that creates pressure. Once the water reaches your house it breaks off into two separate piping systems; one for cold water and one for hot water.
- Cold water — the water coming in directly from the main supply is immediately ready for any cold water needs and connects to the cold water faucets.
- Hot water — this piping system runs to your water heater where the water is heated and then dispersed through another network of pipes running to the hot water faucets.

Drain-waste-vent System
The drain-waste-vent system is the more complex of the two systems. Whereas the water supply pipes bring water to your house using pressure, the drain-waste-vent systems make use of gravity to remove wastewater from the house and to the main sewer line. Paired with the use of gravity, these pipes must have the correct downward angle in order to avoid blockages or clogs due to waste backing up in the pipes.
In addition to angling of pipes this system makes use of several traps, vents and other cleanout systems to ensure that gravity can do its job and that both wastewater and sewage gasses are removed from the house.
- A "trap" is a U-shaped section of pipe that stays filled with water below some sinks. It creates a seal that ensures sewer gases don't make their way into your home. This feature is a major necessity as not only is sewage smelly, but it can also be dangerous to breathe.
- A vent pipe works in tandem with the trap. You've likely seen a metal pipe (or a few) protruding from your roof — these are vent pipes. The plumbing system in your home has to be able to "breathe" in order to work correctly. Otherwise, a vacuum would form and prevent wastewater from moving out of your home. For every trap, there must also be a vent pipe.
- A cleanout is a pipe with a cap that gives access to the sewer line so that blockages or debris can be removed if need be. A blockage can cause sewage to back up into the house so it's important that the cleanout is easily accessible. However, it's important that only a professional works with the cleanout as there are many dangerous fumes and bacteria that can be present.

Once the wastewater makes its way out of your home, it will then be flushed to city sewage centers or to a sewage tank found on your property if you have a well.
How interesting that despite the size of a home or the number of sinks, toilets, bathrooms or kitchens your home has... the basic plumbing concept works in the same way. Two systems — water in and water out. These two systems work together to keep water moving efficiently through your home and then back out. While not an overly complex process, properly planned piping is the key to keeping your water flowing in the right direction. So the next time you turn on the shower, take a moment to appreciate the simple wonders of modern-day plumbing.
Want more advice about all things home — including homebuying or selling advice? Nestiny is a great place for homebuyer education and to help you gauge how ready you are to buy a home. Journey Homeward allows you to enter all your wants and needs while the True Affordability Tool will break down your budget, showing what you can comfortably afford. You will also receive a Ready Report that will give you a vital head start in the home buying journey, saving you valuable time and money.