Hello... New here! We are remodeling our very small bathroom and I want to move our toilet to another area of the bathroom but our closet drain will be about 8 feet away. What is the least amount of slope that my husband can have to make this work for proper flushing? I look forward to being a part of this website. We're always in the midst of construction and in need of information or maybe we can help others by what we learn. Thanks in advance for your help.

All drain pipe must slope slightly downhill, Usually minimum 1/8”
Per foot will be Ok, wait what the other plubming experts has to say, Thanks.

John

Hi Dreamduv:

All plumbing codes in the U.S.A. require 1/4" pitch per foot of pipe for pipes 3 inch and smaller and 1/8" pitch per foot of pipe for 4 inch pipe and larger. That is code, anyway!

4" pipe is rarely used in residential bathroom piping (unless older cast iron pipes) so I'm betting on you having 3" in the floor... ;)

Common sense is important here especially when it comes to drilling any holes in any joists. Do you have drilling to do or is all this in the same joist bay? If piping through joists tell me what size are your joists and also tell me the size of the toilet pipe. You must not notch the joists... ok?

I'm also wondering about the toilet vent here... you said you would be moving toilet 8 feet... may require that you reconnect the sink/vent connection to toilet drain as well.

I don't want to make bigger deal then this is... just want to be sure you are informed of things you need to know.

Let me know what you can..

MARK

Hi Mark... Just a quick answer for you about the joists. My husband is not a computer type of guy so I asked him and he said he has a 4" pipe (house built in 1921) and he does NOT have to drill into any joists he said he has plenty of room. But he wanted me to thank you for thinking about that and he appreciates the help.

Best regards,
Kathy

So in your case I guess we are saying a 2" slope for the new drain, just like John and Mark said. With that being said it may be unlikely that he can get that slope and still connect with the old drain.

Well... Believe it or not, with this old house and this being an addition to this old house. He has to make a 2" variation to make it level. He is not available to help with this answer right now, so with that being said, I think we'll be okay with the 2" slope. Hopefully. If not, we did talk about the posibility of even putting the toilet on a step up. Which could work because we are putting it in a cubby of it's own, separate from the rest of the bathroom. Thanks for your input. Kathy

"in a cubby of it's own" caught my attention. Do you want to know the code requirements for your little cubby?