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Maximum slope for 4” DWV run

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WDH

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I’m building a DIY kit pool house that will have a toilet, sink and an out door shower. There will be a ~100 4” DWV PVC run to tie into an existing detached garage main line.

My Q is about the slope for the 100’ run. I know the minimum is 1/8” per foot slope with most suggesting 1/4”. Is 1/2” too high of a slope? The 1/2” would be for the first ~70’ till a 90 (made up of two 45s 18” apart). The final 20-30’ is at 1/4”.

thanks
 

plowking

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Is the main line at garage going to city sewer or a septic tank? A septic tank the pitch is 1/4 per foot to tank and 1/8 tank to leachfield. Low flow toilets may benefit from more pitch on a longer run Sometimes an extra cleanout in the line wouldn't hurt.
 

Geofd

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Is the main line at garage going to city sewer or a septic tank? A septic tank the pitch is 1/4 per foot to tank and 1/8 tank to leachfield. Low flow toilets may benefit from more pitch on a longer run Sometimes an extra cleanout in the line wouldn't hurt.
extra clean outs is a great idea the more access you have to any drain is only a benefit
 

frodo

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A 4'' line is best run at an 1/8 per foot
you want the water to CARRY the solids away. you do not want the water to leave the solids behind
that just causes problems. the waste dries and then becomes a hump. that will catch a little more each tim . till you have a plug
 

WDH

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I do understand about leaving solids behind. Thus the question

the problem is I put the line in already. If REALLY need to I can ... dig it up and lay flatter with one 45 drops long it.





The main line will be going into a city sewer.

as for clean outs it’s going through the middle of the yard therefore for aesthetics that won’t be possible.
 
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WDH

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I have a c/o at the pool house (within 5’ of exiting pool house) and am tying in into a line that has a c/o two feet after the tie in.

From there it’s a run of about 200-250’ to the city sewer. The 200-250’ run is 80 years old.
 

Geofd

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I have worked on drain that was partially in the yard it was just buried in mulch I had the owner buy an irrigation valve box and we made it look like it belongs there
 

plowking

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1/4 inch pitch recommended here.But I deal with septics not sewers and are afraid of pipes freezing if flow slows down. in winter.
 

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You have no excuse for not installing cleanouts. Just terminate them 10” under sod and lay a piece of ferrous metal on top of them for location.
 
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WDH

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Hey. I wanted to thank everyone. I was debating digging the run back up and relaying at 1/4” with one or two 45 drops. Y’all convinced me to. Along w a buried CO.

I’ll be asking input on another Q shortly
 

Zanne

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You can build a little brick decorative feature over the cleanout (with a removable lid of some sort) if you are worried about aesthetics.. The key is that even if it's buried, you'll need to be able to locate it and access it. They sell little plastic boxes with lids that you sink into the ground and put over stuff like that.
 
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