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Does a Bathroom Sink Need a Vent? (Read This First!)

Venting, a drainage system, works in a way where it equalizes the pressure applied on the drainpipe when water flows downwards. There’s no sink or plumbing fixture out there that doesn’t require venting.

Venting helps the air in the sink to go through the drainpipe with a lot of pressure. If there hadn’t been a venting, the air pressure wouldn’t have been released. As a result, water would have clogged and this process would make the sinks useless.

Bathroom sinks are one of the most used and water flushed sinks. So, it’s like a necessity that they come with vents. You can always find the venting pipe coming from the location of your sink and running through your rooftop.

Does a bathroom sink need a vent?

A bathroom sink needs a vent. In order to prevent the entire plumbing process from the airlock, venting is necessary. Not only does a bathroom sink need a vent, but also the kitchen sink, shower, laundry, toilet, all of the plumbing needs vents. If there’s drainage, there will be vents.

Does a bathroom sink need a vent pipe?

There’s a separate pipe for each vent. These vents for the drainages are joined with other pipes through which the water runs down. So, if there’s a sink in a bathroom, there will be vents. If there are vents, there will be vent pipes.

These pipes are hidden between walls or under the cabinets but you can find them running through your roof opening.

Do I need to vent a bathroom sink?

You undoubtedly need to set up a vent in a bathroom sink. There’s barely any alternative to this. Venting prevents the opposite pressure that clogs water and allows sewer junks to come up through the drainpipe to the sink opening.

So, it’s really easy to concede that venting is necessary. There might be some time when the vent may be jammed and water may clog on the sink. In situations like this, you need to help the venting manually.

Manual venting is nothing but just creating a vacuum pressure with your hands. This creates air bubbles and pushes through the drainage activating the vent again.

What happens if a bathroom sink is not vented?

A bathroom sink that is not vented is problematic and issues regarding this start happening soon after the sinks are being used.

Such problems are –

Unable To Drain Water From The Sink:

If the bathroom sink isn’t vented, water will not be able to go down through the drainpipe because there will be uneven pressure throughout the drainage pipe.

Water Clogging In The Sink:

Vents assure that water isn’t clogging anywhere. So, the absence of vents will make the water clog in the sink. As a result, all of the used water will have no place to go other than clogging in the sink.

Sewer Junks Pop Up:

Sometimes there is opposite pressure from the bottom which makes the sewer junks get sucked up. Therefore, they pop up on the sink through the sink drainage pipe.

Weird Noises From The Drainage:

Ventless drains have this one common issue and that is odd noises from the drainage line. This is also a problem with poorly set vents.

You’ll Have To Vent It Manually:

Having to vent the sink manually can be disgusting and gross. Most people find it discomforting.

You Won’t Be Able To Use The Sink Comfortably:

As the water will clog in the sink, you’ll not be able to use it until the water is drained out of it. Because the more water will be added to the clogged water, the more there will be risks of overflowing from the sink.

As a matter of fact, you’ll find no comfort in this process.

How far can a bathroom sink be from a vent?

The distance between the vent and the bathroom sink should not be much. According to experts, the distance should be within two and a half feet to a maximum of three and a half for a pipe that is one and a half inches in diameter.

How do you vent a bathroom sink? How to install a bathroom sink vent?

Installing a bathroom sink vent is not a simple task. Only professional plumbers or people who have had experiences previously with plumbing can do it perfectly. This is so because any mistake or loose installment can lead to clogging initially and then other serious issues.

The things that you need to install a bathroom sink vent are –

  • PVC Saw or miter saw
  • Permanent ink marker
  • Cement or PVC glue
  • Pipes for drainage
  • P-traps
  • AAV(Air Admittance Valve)
  • Sanitary tee

Step by step guide –

  • Set up the p-trap with the extension of the pipe previously set under the sink.
  • Fix the p-trap with cement or PVC glue.
  • Cut the drainpipe in the recommended length.
  • Join it with the p-trap and fix them with glue or cement.
  • Get a sanitary tee and attach the pipe with the middle leg of the tee.
  • Again, use the glue to fix them.

The sanitary tee comes with three openings known also as legs. The middle one is attached to the pipe.

  • Now attach the AAV as well as the air admittance valve to the upside opening.
  • Connect the other opening or the other leg of the tee to the main drainage pipe.

This is the simplest guide through setting up bathroom sink vents. If in any case you face any difficulty installing, take help from an expert.

Does every bathroom sink drain need a vent?

There are no plumbing fixtures that can work without vents. The toilet, kitchen sink, tubs, and every other drainage line need venting. Water or wastewater cannot go all the way down without the equal division of pressure to help them through.

Air admittance valves are the saviors here. These work with gravity and let the pressure distribute evenly. Vents are the solution to water clogging and jamming.

Can a shower and bathroom sink share a vent?

A shower and the bathroom sink can absolutely share a vent. In fact, a toilet can also share the vent with these two.

All you need to make sure is that the shower is not too far from the bathroom sink and both are within 5 feet. It will ensure hassle-free plumbing and setup. Distance longer than 5 feet can be an obstacle to easy water running.

Does the bathroom sink vent go before or after the P trap?

The bathroom sink vent goes after the p-trap.

So, a p-trap is basically a U-shaped pipe designed to trap the pressure of unnecessary water or sewer gases. The vent is set after this particular p-trap and before the drainage pipe.

There’s usually a sanitary tee to connect all these three openings- the p-trap, the air admittance valve, and the sewerage.

P.s. In some cases, people prefer adding two p-traps for a more controlled air and water pressure.

What size vent for bathroom sink plumbing?

The perfect size vent for the bathroom sink is 1 ¼ inch wide in diameter. The vent size doesn’t differ much. What differentiates is that the diameter of the drainage line and the distance of the placement of the vent; how distant they can be.

If the drainage pipe is 1 ¼ inch in diameter, the vent should be within 2 and a half feet. And if the drainage pipe is 1 ½ inch wide in diameter, the vent should be within 3 and a half feet.

Are bathroom sinks vented?

In most houses, the plumbing setup comes with vents be it in the kitchen sinks or the bathroom sinks. Bathroom sinks are already vented.

But if in any case, you think you’re facing troubles with proper venting and water clogging, go look for a plumber and set a vent as soon as possible.

How do I know if my sink is vented?

Sinks without vents have problems from the beginning. So, if you have a bathroom sink that clogs every now and then, makes odd noises, gases come up, bubbles, or any such unusual happenings, you should know that your sink isn’t vented or probably not perfectly set.

On the other hand, if you see water draining without clogging, you should know that your sink is perfectly vented.

Final Thoughts:

Air admittance valves save you from the disturbance that you can often feel if there’s water clogging every other day.  So, venting is necessary and the alternatives are only exaggerations. So, without any sort of rethinking, you should install a vent for your sink. 

Frequently Asked Questions:

Are Bathroom Sink Drains a Standard Size or Universal?

Can You Drink Bathroom Sink Water?

Can Bathroom Sinks be Reglazed?

Can a Bathroom Sink Be Moved?

Do Bathroom Sinks Need a P Trap?