Does every plumbing fixture need a vent?

Author: Prof. Harrison Cruickshank  |  Last update: Wednesday, September 24, 2025

Plugged at the U-pipe, the fresh water blocks sewer gases and lets them harmlessly leak out the plumbing vents. Every plumbing fixture needs to have a vent to work properly. Bath tubs, toilets, washing machines and kitchen sinks need the biggest plumbing vents.

What can happen if a fixture is not vented?

Some types of broken ventilation can even actively suck up sewer gas and release it through your sink drain or toilet bowl. When this happens, stinky sewer gas will enter your home.

Will plumbing work without a vent?

If you didn't have vent pipes, the wastewater going down your drains would empty your traps because of a vacuum effect. When this happens, toxic sewer gases can seep into your house. So, you want some of the draining water to stay in the trap while the rest goes down the drain.

What are the rules for plumbing venting?

In general, the vent should be as close as possible to the fixtures it serves. This proximity helps ensure the vent can effectively equalize air pressure and prevent sewer gas entry. However, there are some common guidelines to consider: The vent should be within 5 to 6 feet of the fixture drain it serves.

Can a shower and toilet share a vent?

Yes, the toilet and sink can share the same vent, as can the shower. It's common to have one main vent pipe for multiple fixtures, although you might need a larger pipe. You should check with local building and plumbing codes to confirm you'll have adequate piping for your home.

What is a Plumbing Vent? (and Why Do You NEED it?)

Is it against code to not have a vent in a bathroom?

Surprisingly, some building codes do not require bathroom fans. All municipalities have different requirements, but some do not draw a hard line on requiring exhaust fans. Bathroom ventilation is needed in those areas, but it can be from a window or fan—you choose.

What happens if you don't vent a shower?

All plumbing in your home must have vents to remove sewer gasses and regulate air pressure in pipes. When liquid goes down a pipe, air needs to follow it. Without the vent pipe, the liquid will attempt to draw air through the P-traps on your tub or sink. This will create a gurgling sound.

Does each fixture need a vent pipe?

Every plumbing fixture needs to have a vent to work properly. Bath tubs, toilets, washing machines and kitchen sinks need the biggest plumbing vents.

What happens if plumbing not properly vented?

Poorly-vented drain lines will not be able to effectively move wastewater and solid waste out of your building. This could lead to problems such as overflowing drains, backed-up toilets, and similar plumbing issues.

What is the alternative to plumbing vents?

AAVs are a great alternative if you can't connect to an existing venting system due to complex pipe routing issues or obstructions – an ideal venting solution for island sinks, remote bathroom groups, home remodels and additions that would otherwise have to be tied into a stack vent utilizing specialized venting ...

Will a toilet flush if not vented?

If you have downward-sloped pipes, your toilet will most likely work without a vent. Gravity does a lot of the heavy lifting anyway.

Can I run a plumbing vent out the side of my house?

The good news is that your plumbing vent can indeed be run horizontally. When figuring out how to lay the pipes within your walls, it's more important to remember the clearance that is required by your spill line (the point where water overflows a tub, sink, or toilet).

What happens if a bathroom doesn't have a vent?

Stuffiness when you enter the room. Mildew on walls or tiling. Stains forming on walls or ceiling. Smells that linger for a long time.

Does every sink drain need a vent?

Yes, every drain needs a separate vent to ensure the plumbing works properly and waste is removed. What happens if a drain isn't vented? Without drain vents, gases build up in plumbing pipes and drains and keep water from flowing freely.

Do old houses have plumbing vents?

The vent allowes air to get behind the water so that it can move steadily down the drain. Being that the drain can not work properly without a vent, older houses do have a vent. You are just not seeing it!!! Modern houses usually have a 3 inch main drain with smaller drains attached to it.

Does toilet plumbing need a vent?

The fixture cannot drain effectively if there are no vent pipes connected to them. For example, in a bathroom fixture group, if you flush the toilet and there is no vent to that toilet, or the vent is not working properly, it may suck the water out of the trap on the bathtub.

Can a washer and toilet share the same drain?

Your drains are connected – One of the main reasons your toilet gurgles when your washer machine drains is because your washer machine is connected to the toilet drain. This isn't uncommon. Your washing machine might have been placed in between your toilet and sewer stack.

Can two sinks share the same vent?

A horizontal wet vent could have as few as two fixtures or as many as ten fixtures but not more than two fixtures of any type can be connected to the system.

How do I know if my plumbing is properly vented?

Signs of a clogged or blocked vent include gurgling sounds from drains and toilets, slow-draining fixtures, foul sewer odours around sinks and drains, decreased water pressure, and bubbles coming up through the toilet bowl. A clogged vent pipe prevents proper airflow and allows sewer gas to back into the home.

What happens if plumbing is not vented?

The same thing happens when you don't vent your plumbing. It will not drain properly. You also run the risk of the water in the p traps being siphoned out. This allows sewer gas into the home.

Can multiple plumbing fixtures share a vent?

It depends on the distance between each plumbing. If they are too close to each other, they can share. If they are away from each other, vents are separated.

Does a shower need to be vented?

Venting is necessary for bathroom plumbing systems to prevent blockage. All pipes in your home, particularly for toilets, sinks, and showers, require proper venting. It protects the trap on the drain pipe. In addition, it helps you secure your wallet, fittings, time, and even the pipe itself.

Is it healthy to not vent?

Indeed, a 2020 study of coping strategies during the pandemic found that venting was linked to poorer mental health, while tactics like accepting, joking about, and positively reframing the situation seemed to boost well-being. “You should generally act how you hope to feel,” Cougle says.

Does every bathroom need a vent?

Yes, every bathroom needs to be ventilated. It is required by code in many places for building contractors to ensure adequate ventilation in bathrooms. They do not always do so.

Do all houses have a plumbing vent?

They're those pipes sticking up out of the roof that run through the attic and through the rest of the house. All residential plumbing fixtures need to be protected by a plumbing vent.

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