Why vent toilet through sink?

[Ted cark]

Why not just vent through main vent? Is it because toilet is usually more than six feet from main vent.

 

[wwhitney]

In the diagram below, either the left or the right are plausible. The US plumbing codes (which vary by state) regulate the length of the red line (the lav trap arm), and some of them regulate the length of the green line (the WC fixture drain up to its vent). So the advantage of the left is just that those distances are shorter in that diagram and the right may not meet the requirements.

Cheers, Wayne

 

[Sponsor]

 

[Ted cark]

Thanks

 

[Plumber69]

And you can wet vent a toilet and tub or shower thru the sink

 

[Sylvan]

AWFUL VENTING . the installer obviously had no formal education and looked at how cheap he /she could do the job

A "WET VENT" becomes reduced over the years by soap scum and other debris that reduces the flow and vent capacity as the inside diameter is reduced.

Ideally a vent shall be placed with in 2 feet of a trap and the trap with in 2 feet of the fixture