The Basics on Drains, Traps and Vents

Drains and proper drainage are important parts of any home. Learn about the different types of drains, traps and vents, and how they work in a typical house.
different drains,traps,vents found in typical home

different drains,traps,vents found in typical home

Figure A

Figure A

Related To:

Whenever water comes into a home, it has to have a way to leave after it's been used. This is where the importance of drains and proper drainage comes into play. Most homes utilize the same basic principles for plumbing and drain systems: A main water line usually comes in around the home's foundation; from this point, it runs over to a water heater. The water heater generates hot water for the entire house. From the water heater, hot and cold water lines run throughout the house, supplying each of the fixtures with water.

Most people don't realize how a home drainage system works; they assume that when they release water from the sink or flush a toilet, the water just goes away. Although this is partially true, a little more is involved in the process of removing waste water from the home. Each fixture has its own drain line; each of the drain lines ties into a larger main line, which takes the water out of the house.

People who live in urban and suburban areas and get their water from a municipality usually have their waste water drain into a sewer system. Septic tanks generally need to be pumped out every 10 years or so to prevent backup, which can cause problems with the home's drainage system.

The most important component of a drain, which most people take for granted, is the trap. They're called traps because they do just that: trap water inside, preventing sewer gases from coming back into the house.

Several connections are needed when connecting a trap. First is the nut, which connects two pieces together with a threaded fitting. A ferrule forms the seal; the nut simply screws down over the ferrule to form a water tight seal.

Vents are a major component in a home's drainage system. Venting allows water to pass out of the drains easily. Today, houses are vented through the roof. Roof flashing, made from heavy grade rubber, lead or sheet metal holds the vent pipe in place.

Another thing to consider is pitch. Pitch simply means the angle in which water will flow easily and gradually with the help of gravity. Every drainpipe, whether underground or in a wall, must have some type of pitch and be sloped properly to allow wastewater leaving the home to drain out. To ensure water will drain properly and won't back up in the line, a good rule of thumb to follow when installing pipe is a drop of 1/4 inch per foot.

Keep Reading

Next Up

Powered Drain Snake

This powered drain snake has a long length of flexible metal with teeth on the tip that can help cut through roots clogging drains.

Basic Pipe Tips

The plumbing system in your home is simpler than you might think. Find straightforward information about pipes, fittings and the fundamentals of plumbing repair.

Basic Plumbing Tools

Occasionally challenges such as clogs or leaks arise which a do-it-yourselfer would like to remedy quickly. Specific tools are necessary for these types of repairs.

How to Install a French Drain

Prevent water from gathering in unwanted places by installing a French drain to redirect it.

The Basics of Air Conditioning

Shopping for a new HVAC system? Here are a few pointers to help you choose an air-conditioning unit based on efficiency, climate and noise.

Heating Your Home: The Basics

Learn the basics about heat pumps and furnaces.

Water Filter Basics

If the water from your faucet has an undesirable taste or odor, installing a water filter can make a noticeable difference. Host Ed Del Grande gives the basics on four of the most common types of household water filters.

Radiant Floor Heating Basics

Alternative heating can include more than adding a fireplace or two or some space heaters. Radiant floor heating is an innovative heating method that works in an unusual way but is highly efficient.

Watering the Lawn: Zones and Other Basics

Learn about everything related to installing a home irrigation system.

Gas Fireplace Basics

Gas fireplaces are a great way to add warmth and comfort to a space. Much like wall furnaces, gas fireplaces come on and off with a wall switch and can be controlled by a remote.

On TV

Breakneck Builds

7:30am | 6:30c

Lawn & Order

8:30am | 7:30c

Lawn & Order

9:30am | 8:30c

Lawn & Order

10am | 9c

Lawn & Order

10:30am | 9:30c

Lawn & Order

11am | 10c

Lawn & Order

11:30am | 10:30c

Rehab Addict

12pm | 11c

Rehab Addict

12:30pm | 11:30c

Rehab Addict

1pm | 12c

Rehab Addict

1:30pm | 12:30c

Rehab Addict

2:30pm | 1:30c

Rehab Addict

3:30pm | 2:30c

Rehab Addict

4:30pm | 3:30c

Rehab Addict

5:30pm | 4:30c

Rehab Addict

6:30pm | 5:30c

Rehab Addict

7:30pm | 6:30c
On Tonight
On Tonight

Stone House Revival

8pm | 7c

Stone House Revival

8:30pm | 7:30c

Stone House Revival

9:30pm | 8:30c

Wood Work

10pm | 9c

Wood Work

10:30pm | 9:30c

Wood Work

11pm | 10c

Wood Work

11:30pm | 10:30c

Stone House Revival

12:30am | 11:30c

Wood Work

1am | 12c

Wood Work

1:30am | 12:30c

Wood Work

2am | 1c

Wood Work

2:30am | 1:30c

Stone House Revival

3:30am | 2:30c

Renovation Realities

4:30am | 3:30c

Get Social With Us

We love to DIY. You love to DIY. Let's get together.

Consult Our A-Z Guide

Everything You Need to Know

Browse a full list of topics found on the site, from accessories to mudrooms to wreaths.  

How-To Advice and Videos

Get video instructions about kitchens, bathrooms, remodeling, flooring, painting and more.

Watch DIY Downloads Now

Watch DIY Network LIVE

Don't miss your favorite shows in real time online.