How to Vent a Toilet?- Here’s The Solution!

Every toilet needs a ventilation system to pass the odors and keep the water flow healthy. So, if your toilet doesn’t come with a vent, you should install it on your own as soon as possible. You can also seek professional help for that but we can help you show how to do it too. 

So, the question is, how to vent a toilet?

You need to install one vertical vent pipe to the peak of your roof that will vent the entire system. The waste pipes will receive air through that open pipe, which is connected to the sewer, waste, and pipes.

Our article covers a detailed discussion on this topic and process. So, let’s dive into the article without any further ado. 

Does a Toilet Need to be Vented?

Yes, all toilets must have appropriate ventilation in the form of a window or, preferably, an exhaust fan in accordance with residential building requirements.

a toilet with exhaust fan as ventilation

The air from your toilet ought to have ventilation that pushes the old air outside where new air can take its place, in accordance with the IPC building code, which is applicable to the great majority of the country. To just move the air within is insufficient. 

The air needs to be exhausted outside. If you decide to use a ventilation fan, it must move air at least 20 cubic feet per minute continuously or 50 cubic feet per minute intermittently.

However, the majority of people pick an exhaust fan with an intermittent rating of at least 80 cfm.

Be cautious about the choices you make only to save a few bucks because even though your fan satisfies the minimum standards, it might still not be eligible when the code is revised.

To ensure that the air in such spaces is fresh-smelling and clean, you need sufficient ventilation in all restrooms. Toilets frequently have significant moisture levels because of the plumbing necessary to run the toilet.

Additionally, due to their small size, restrooms require better ventilation than many other rooms. Mold growth and other water damage are prevented by proper air movement.

In addition to being pricey, repair work can also be dangerous for your skiing, eyes, and respiratory system because of the airborne mold toxins. Additionally, it maintains the air clean in a confined area that is frequently blocked off, making the experience more pleasant.

How to Vent a Toilet?

You are aware that everything on the globe, including our toilets, is impacted by atmospheric pressure. To ensure the proper operation of the water supply and sewage systems, that pressure must be balanced in the waste pipes.

That’s why venting your toilet is really necessary and can not be avoided. But if you don’t know how to vent a toilet it’s completely fine. Because we came forward to show you how you can vent your toilet with your own hands. Let’s read below and follow these steps.

Step 01: Run the Toilet Drain Pipe

The toilet flange, which you can see from the outside, is where the drainage system for the toilets begins.

By reducing it by 3″ on the elbow, you need to attach a 4″ toilet drain pipe to the flange. The reduction facilitates the free movement of garbage. The pipe leading from the toilet’s base to the waste pipe is depicted in a toilet drain pipe diagram.

Step 02: Connect to the Waste Pipe

Fix a trap arm pipe that extends horizontally from the flange at the end, where you have lowered the elbow to 3″. Before linking to the vent, the trap may be allowed to flow under locations with no restrictions on plumbing. 

The waste pipe must have an incline for the wastes to flow downhill and the gasses to flow upward, much like in the toilet plumbing diagram above.

The toilet vent distance in places subject to UPC standards should be 6 feet. Follow the trap-vent distance specifications while installing to avert remodeling once the authorities find out.

Step 03: Connect the “Y” Bend

Connect the “y” curve when it is at the ideal distance. The link touches the ground trap and the vertical vent that goes upward over the roof, forming a Y shape.

To ensure that the vent and the trap operate at their peak efficiency without clogging the elbow, glue the connector at the proper angle.

At this stage, if you’d like, you can connect a reducer to lower the vertical end to 2″ while leaving the trap edge at 3″. Again, avoid lowering it to 2 if you reside in locations with UPC limits. Let the Y connector stay at 3 instead.

Step 04: Connect the Vent

connecting the vent pipe to the vertical Y edge
Image from Joseph Peachey Plumbing & Heating Services

Connect the vent pipe’s right side at the vertical “Y” edge, extending it far enough to pass through the roof. Ideal connector placement is at the edge, where the vent will follow a wall. Ideally, either the outside or, if inside, the farthest corner.

Follow the UPC regulations once more regarding vent size, although ideally, the pipe shouldn’t be any smaller than 2″.

Make sure all the fittings are done correctly. But first, think about your ground’s gravity and slope. With correct installation, the vent should safeguard the trap seals and maintain adequate aeration throughout the whole drainage system.

What to Consider Before Installing a Toilet Vent?

You can’t just start venting your toilet with a step-by-step manual found on the internet. You need to consider some important factors about your toilet and then you should move forward with your tools. 

Now let’s read below to see what you should consider before venting your toilet.

Vent Pipe Size

You must take into account the best vent pipe size for your toilet as there are various sizes available.

A vent pipe should ideally be at least a 2″ PVC pipe. An extended line is essential to ensure that air can freely enter and exit the system. You should always follow the bathroom vent pipe size, which is 2″. Any smaller than that won’t do the job adequately.

Toilet Drain Size

You must check the size of your toilet’s outflow. This will assist you in choosing the appropriate vent pipe size.

toilet drain pipe

The typical toilet drain size is 3″, as this size is thought to permit unobstructed passage of human waste. Others, though, are larger than 3″. Therefore, more waste may move through a drainpipe without clogging the longer it is.

For example, a 4″ drain size can accommodate waste that is double the size of a 3″. A large drain size necessitates an equally large venting size.

Toilet Trap to Vent Distance

The ideal distance is 6 feet between the vent and the toilet trap. This indicates that the vent feeds the trap within a 6-feet radius.

The flow of the waste and the amount of air required to keep the sewer gasses from retracing may be impacted by how near they are to one another.

For the sake of motion and flow, you need to put enough space between the two.

Fixtures to Serve

With one vent pipe, how many utilities do you plan to serve? You will require more vent pipes as your restroom facilities and patrons grow.

Building Codes Requirements

The installation of your toilet venting system is governed by both national and local construction codes. Stay away from being a non-compliance victim. Additionally, some are more thorough, therefore it’s important to check your local building codes. 

The requirements are always specified. Most UPC codes stipulate that the vent pipe must be smaller than 1.5″.

You should get the most recent version of the codes to prevent renovation when you make a mistake.

How Do You Vent a Toilet Without Going Through Roof?

There is no need for your plumbing vents to pass through the roof. Although plumbing vents most frequently run via roof stacks, they can also be installed through an exterior wall. 

toilet vent through a wall

The requirement is that the plumbing vent must extend higher than the home’s tallest window. Your municipal ordinance may specify that your plumbing vent must be 12 feet from the wall in particular circumstances.

Some structures can employ alternatives to venting through roofs. You can place the main stack in the wall according to some country’s building rules, but you should confirm this with your plumber.

There are other options to think about if you just cannot or would prefer not to vent via your roof, such as:

  • Air Admittance Valves (AAVs)
  • Venting through an exterior wall
  • Loop venting

The most common alternative to roof-based vents is air admittance valves. The air vent has the same function as the cheater valve, although it operates slightly differently. Instead of using gravity to balance liquids and gasses, it generates pressure.


What happens if a toilet is not vented?

Your ventilated drain pipes can’t effectively remove solid waste and wastewater from your building. As a result, there can be overflowing drains, clogged toilets, and other plumbing problems in your toilet.

Can sink and toilet share vent?

Yes. But generally, a toilet wet vent can only be used to vent two fixtures at a time. The dimensions of the toilet drain, sink drain, shared sink/toilet vent area, and vent going up should be 3 inches, 1.5 inches, and 2 inches, respectively.


Thanks for coming this far with our article. Hope our piece could help you figure out how to vent a toilet. Now that you know all the proper steps, you can easily vent your toilet all on your own without anyone’s help.

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