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toilet drain to vent pipe distance

I'm plumbing in a new bathroom (toilet/sink/shower). This bathroom backs up to an existing bath so most of my plumbing is pretty clustered. I have the sink going up a 1-1/2 inch vent and the shower with a 1-1/2 inch vent with the drain headed towards the toilet.

My question is: The new toilet is using a 4 inch drain and is 7 feet away from the the main vent stack which is also 4 inches in diameter. Is this vent sufficient or is it necessary to get a smaller vent closer to the new toilet drain?

My book says that with a 4 inch drain, the max distance to the vent is 10 feet, but I'm trying to make doubly sure as a 2 inch vent would end up swiss cheesing the (non-load bearing) 2x4 wall that separates the 2 bathrooms.

Thanks inadvance for yer help.

Re: toilet drain to vent pipe distance


I am also in a similar situation. My wife wants to relocate a shower and swap locations of the sink and toilet. Can I reuse the existing vent pipe? The vent pipe now handles all 3 fixtures, and is located right off the toilet. Currently, the sink and shower drain past the toilet.


Re: toilet drain to vent pipe distance

If you are reading the Uniform Plumbing Code I think what you are refering to 10' is the max distance of a 4" trap arm. The max allowable distance from a toilet to it's vent opening is 6'
Depending on waht code you are using. The International Residential code states that you can put in a studer (quick) vent as long as you have a stack vent going through the roof some where in the house. Hope this helps

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