I need advice on a plumbing code question. My existing 1st floor bathroom vanity appears to use the drain from the 2nd floor toilet as a vent stack. Appears that both 1st and 2nd floor toilets have no other fixtures draining into their respective drains.
Question: does the plumbing code allow me to route the 1st floor vanity drain into the same drain from the 2nd floor toilet (which is being used as a vent for the same vanity)? Or must I continue to have a dedicated drain for toilet?
See sketch at: http://farm3.static.flickr.com/2416/1814061886_24cf91d8d3_b_d.jpg
(If this is not the appropriate way to reference an image on this newsgroup, please advise and I'll change).
Your comments are appreciated. Regards,