Highbeam
Super Member
Re: 3\" or 4\" main septic line?
4" diameter for the final run. That's the right way to do it.
4" diameter for the final run. That's the right way to do it.
3" or 4" main septic line?
- Thread starter 5030tinkerer
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Highbeam
Super Member
Re: 3\" or 4\" main septic line?
4" diameter for the final run. That's the right way to do it.
4" diameter for the final run. That's the right way to do it.
OP
5030tinkerer
Gold Member
Re: 3\" or 4\" main septic line?
The same builder told me that the drop should be 1/4" every 10 feet where everything I have ever, ever read says 1/4" every foot. Perhaps with a drop of only that 1/4" every 10' you need the smaller pipe to keep things going. That minimal of a drop seems to me to be almost the same as flat!
The same builder told me that the drop should be 1/4" every 10 feet where everything I have ever, ever read says 1/4" every foot. Perhaps with a drop of only that 1/4" every 10' you need the smaller pipe to keep things going. That minimal of a drop seems to me to be almost the same as flat!
OP
5030tinkerer
Gold Member
Re: 3\" or 4\" main septic line?
The same builder told me that the drop should be 1/4" every 10 feet where everything I have ever, ever read says 1/4" every foot. Perhaps with a drop of only that 1/4" every 10' you need the smaller pipe to keep things going. That minimal of a drop seems to me to be almost the same as flat!
The same builder told me that the drop should be 1/4" every 10 feet where everything I have ever, ever read says 1/4" every foot. Perhaps with a drop of only that 1/4" every 10' you need the smaller pipe to keep things going. That minimal of a drop seems to me to be almost the same as flat!
midlf
Platinum Member
Re: 3\" or 4\" main septic line?
We had the plumbers in to replace the main line through our basement. They were EXTREMELY careful to set the slope at 1/4" per 10'. They said too much slope and the liquid leaves the solids behind. Too little and the solids settle out. Apparently with the right pitch those two tendencies balance out. We had a cast iron line replaced as the sewer gas corroded the inside at the top because it would never get washed. A 3" line would not get washed either although we did not discuss it as we have full flow toilets that the spouse will not let me change out, even with the horrid colors because she does not want "those toilets that don't flush". 4" is code for the number of fixtures we have.
We had the plumbers in to replace the main line through our basement. They were EXTREMELY careful to set the slope at 1/4" per 10'. They said too much slope and the liquid leaves the solids behind. Too little and the solids settle out. Apparently with the right pitch those two tendencies balance out. We had a cast iron line replaced as the sewer gas corroded the inside at the top because it would never get washed. A 3" line would not get washed either although we did not discuss it as we have full flow toilets that the spouse will not let me change out, even with the horrid colors because she does not want "those toilets that don't flush". 4" is code for the number of fixtures we have.
midlf
Platinum Member
Re: 3\" or 4\" main septic line?
We had the plumbers in to replace the main line through our basement. They were EXTREMELY careful to set the slope at 1/4" per 10'. They said too much slope and the liquid leaves the solids behind. Too little and the solids settle out. Apparently with the right pitch those two tendencies balance out. We had a cast iron line replaced as the sewer gas corroded the inside at the top because it would never get washed. A 3" line would not get washed either although we did not discuss it as we have full flow toilets that the spouse will not let me change out, even with the horrid colors because she does not want "those toilets that don't flush". 4" is code for the number of fixtures we have.
We had the plumbers in to replace the main line through our basement. They were EXTREMELY careful to set the slope at 1/4" per 10'. They said too much slope and the liquid leaves the solids behind. Too little and the solids settle out. Apparently with the right pitch those two tendencies balance out. We had a cast iron line replaced as the sewer gas corroded the inside at the top because it would never get washed. A 3" line would not get washed either although we did not discuss it as we have full flow toilets that the spouse will not let me change out, even with the horrid colors because she does not want "those toilets that don't flush". 4" is code for the number of fixtures we have.
Re: 3\" or 4\" main septic line?
I think you meant to say 1/4" per foot, not 10'
Recommended pitch is 1/4"-1/2" per foot. To shallow and the flow is insufficient, and too steep and the high velocity can leave solids behind.
paul
I think you meant to say 1/4" per foot, not 10'
Recommended pitch is 1/4"-1/2" per foot. To shallow and the flow is insufficient, and too steep and the high velocity can leave solids behind.
paul
Re: 3\" or 4\" main septic line?
I think you meant to say 1/4" per foot, not 10'
Recommended pitch is 1/4"-1/2" per foot. To shallow and the flow is insufficient, and too steep and the high velocity can leave solids behind.
paul
I think you meant to say 1/4" per foot, not 10'
Recommended pitch is 1/4"-1/2" per foot. To shallow and the flow is insufficient, and too steep and the high velocity can leave solids behind.
paul
Ken_CT
Gold Member
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- BX23, Hustler Mini Fastrak 42 w/mulch kit, Wheel Horse 14-38XL
Re: 3\" or 4\" main septic line?
Attached is a chart for drainage pipe pitch from the 2003 International Plumbing Code Book. For a four bath home a 4" building drain would be a better choice.
Attached is a chart for drainage pipe pitch from the 2003 International Plumbing Code Book. For a four bath home a 4" building drain would be a better choice.