3" vs. 4" PVC toilet branch run???

Old 01-17-10, 05:50 AM
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3" vs. 4" PVC toilet branch run???

So all the books and such I have suggest I use 3" PVC for a toilet branch arm in the basement floor. My new toilet drain will be pretty close to the stack and I planned to just use 4" all the way thru.

Is there a really good reason to use 3" instead of 4"?
Old 01-17-10, 02:33 PM
Join Date: Dec 1999
Location: San Diego Ca. USA
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Hi, Many years ago I read an article about the size of pipe which made sense to me. If the pipe is too big water will not fill the pipe and leave solids behind and thus causing plugged lines. With todays low flow toilets that use less water it is the same as using a bigger pipe..... less water flow. I would use the three inch.
Good Luck Woodbutcher

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