DWV Route Question

Started by retiredmarine, June 04, 2019, 11:09:35 AM

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Here's a quick sketch of my waste line. The main line is 3" to the Septic with the kitchen, laundry, and bathroom connecting to it.  I wondering if I'll have any problems with the toilet waste draining with the 45 degree bend? it's a single story and all of this will be in the crawlspace.


It basically looks good to me. The main line should be 4", though (the hole in the septic tank should be 4"). I would keep that line at 4" until you get to that toilet.. you can even run 4" to the toilet itself it you're worried about it, - toilet flanges typically glue outside 3" or inside 4" line. I personally oversized everything, I ran 2" to sinks/tubs/washer then put a bushing in when I came out of the wall. In addition to helping with clogs, it makes any venting problems go away too.

Also a shower drain is 2", a tub drain is 1.5".


I thought this book was great for plumbing. He really spells it all out and doesn't get lost in the code... which the code was pretty indecipherable to me. I basically did what he said and have not had a single issue (yet :))


Thanks Nathan!  I'll check that book out.