WELCOME TO RIVER DAVES PLACE

Residential Plumbing Question - detached garage bathroom

DalesSpeed

Well-Known Member
Joined
Apr 4, 2009
Messages
88
Reaction score
143
I’m getting ready to rough in plumbing to the new detached garage this week. I need to go 76’ for the sewer/toilet drain to connect to the house and I’m running a 3” line. Can I go 1/8” per foot using 3” or do I need to go 1/4”?

I’m located in San Bernardino county.
 

hallett21

Well-Known Member
Joined
Nov 9, 2010
Messages
10,573
Reaction score
8,168
Not a plumber but I always was told 1/8th per ft on 4” and 1/4 per ft on 3”


Sent from my iPhone using Tapatalk
 
Last edited:

2FORCEFULL

Well-Known Member
Joined
Jan 26, 2008
Messages
27,016
Reaction score
14,024
I have a similar problem at my havasu house ,the detached garage i wanna build is about 70' to the bath,... I was thinking the min would be about 8'' to bottom of pipe,... that would mean about 30'' min to connection...this video shows what min would look like..

 

2FORCEFULL

Well-Known Member
Joined
Jan 26, 2008
Messages
27,016
Reaction score
14,024
on mine the shower would be to the right, and where the vent is for toilet , there will be a kitchen sink on the other side of the chase wall.. looks like there is about 4' to the san t for the drain... my concern is that if the plumbing backed up it would fill the shower with waist,.. being this video is a basement there must be a pump involved... pretty sure I will have to do a pump, or a separate septic and not hook to sewer... been scratching my head on this problem...
 

2FORCEFULL

Well-Known Member
Joined
Jan 26, 2008
Messages
27,016
Reaction score
14,024
almost every way to plumb to code eats up alot of the fall,.... maybe a real plumber can chime in..., but I think I will have a problem ....

 

Spudsbud

Well-Known Member
Joined
Jun 3, 2012
Messages
2,660
Reaction score
4,240
Thats a long way. I'd go 4". Spend little more now to avoid drain rodding problems down the road. Dont forget a couple clean outs along the way......
Not a plumber but retired Pipefitter 40 yrs.
 

Drew

Well-Known Member
Joined
Oct 13, 2015
Messages
339
Reaction score
675
You can go 1/8 on 4”. I’m a licensed plumber for 30 years
 

DirtyWhiteDog

Well-Known Member
Joined
Feb 16, 2013
Messages
673
Reaction score
654
That is a long run for 1/8" per foot, the water will out run the browns. As long as you remember to shower last or give an extra flush every once in a while and before leaving for awhile, it will be fine. Also, yes you need an end of line clean out, behind your last connection, and a 2 way clean out before you hook into the building sewer.
 

Drew

Well-Known Member
Joined
Oct 13, 2015
Messages
339
Reaction score
675
Technically no. Never reduce on downstream . I have run 1/8 pitch on 3” in the past when it was absolutely necessary. Just make sure you don’t use a 1.28 gl flush toilet. Need a good flushing toilet and you can manipulate it to flush with more water by lowering the float on the flapper on American standard bowls or on Kohler some of them you can raise the water level. So basically don’t buy a POS toilet
 
Top