What is a wet vent?


If you have ever manually installed a toilet, sink or drain yourself, then you are most likely familiar with the term “venting.” If you don’t know what that term means, that’s okay because we will break it down for you in this article.

In all plumbing systems, water and waste are transported through a network of pipes to drain into a sewer or septic tank. The vaporous remnants from the waste humans create need somewhere to go as well. If the gas created from the waste is not vented properly, the gas and odors can make their way back into the home through the drain and plumbing fixture (sink, tub, shower, or toilet) that is not vented correctly. Vent pipes plumbed at the right locations prevent waste water from being siphoned out of your p-traps. If a p-trap is siphoned dry, then the gas and odors have no water barrier to keep them from finding their way back into the home. Vent pipes also equalize the air pressure within the plumbing system to keep water and waste moving through the drain. Venting allows the gases to escape vertically out through the roof.

What is a wet vent?

If everything was perfect in the world, then vents and drains would always be separate. Basically, venting from one plumbing fixture isn’t blocked by the waste from another. Unfortunately, this isn’t always the case, but fortunately there are instances when this is a benefit. If you wanted to install a new sink or shower in your bathroom, but running a normal vertical vent through the wall isn’t an available option due to structural obstacles, then you should consider a wet vent. To summarize, a wet vent is a drain pipe that doubles as a vent pipe. Wet venting can only be done with a vertical vent, not a horizontal vent. Vertical wet venting can be used for multiple fixtures that directly connect to the main vertical vent pipe. If the drain pipe from your sink connects to the vertical vent pipe around a foot above where your toilet connects, the section of pipe between each connection acts as both a drain and a vent, and this serves as a wet vent. The difference between a dry vent and a wet vent, is that a dry vent only supplies air to the drain line, while a wet vent will function as both a drain line and a vent.

Be cautious

Before you take the plunge, and start installing piping that creates a wet vent, you need to do your research. Most municipal codes are very strict when it comes to wet vents. More often than not, such codes will dictate that the size of a wet vent’s pipe must be larger than normal. In addition, all plumbing fixtures attached to the wet vent have to be on the same floor. Lastly, it is imperative that toilets be installed downstream of all the other fixtures. If you are considering a wet vent, you should contact a local plumbing professional for clarification of the regulations in your area.

Advantages of wet vents

If you plan on doing any type of remodeling, chances are you are going to have to consider how your plumbing fixtures will be vented. Because of the way fixtures are situated, connecting them to the main vent pipe can make the installation very tricky. If you find yourself struggling to properly dry vent your plumbing fixtures, then opting for a wet vent may be your best option. Another advantage to wet vents are that they require fewer parts and take less time to install. If you are able to install them yourself, you will save money on both parts and labor. If you ask any plumber about wet vents, they will likely say how useful they can be. Wet vents can definitely be the lifesaver you need when there are no other options left.

Municipal code and regulations regarding wet vents can vary greatly based on where you live, so doing your research can only help you in the long run. The last thing you want to do is put in a lot of work only to find out it doesn’t comply.

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