4" Gutter -> 3" Sewer Pipe - Plumbing - DIY Home Improvement | DIYChatroom

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Old 08-17-2009, 07:30 PM   #1
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4" gutter -> 3" sewer pipe

i was contemplating a redesign of my gutter system and was wondering if it would be to constricting to conduct my 4 inch gutter into a conveniently located 3 inch pipe that is buried nearby ?


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Old 08-19-2009, 08:03 AM   #2
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It might overflow in the heaviest of rain storms.

WHere does the 3 inch pipe lead to?

Do not run rain water or gutter water into a septic system or into a dry well used for household drains. Also do not run into a perimeter drain (aka French drain, weeping tile) system for the house unless you have a sump pump and need/want that to help get rid of the water.


The good conscientious technician or serviceperson will carry extra oils and lubricants in case the new pump did not come with oil or the oil was accidentally spilled, so the service call can be completed without an extra visit.

Last edited by AllanJ; 08-19-2009 at 08:07 AM.
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Old 08-19-2009, 11:48 AM   #3
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I don't think you'll have a problem. A 4" gutter doesn't empty into a 4" round downspout; the outlet on a 4" gutter is likely a 2"x3" oval (6 sq in) at best. A 3" round PVC will be 9.4 sq in. If it overflows, then think about replacing the 3" but I doubt it will.
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Old 08-22-2009, 09:05 PM   #4
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It really depends on how much square footage of roof your draining into that 4" gutter. But unless it's a really big area draining into that gutter, I would imagine a 3" drainage pipe would be fine.

I have a modest sized ranch home (approz 1200 square feet) and my rear downspout drains into a 3" pipe. The pipe steps up to 4" where my front downspot ties into it. No problems with the volume.
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Old 08-22-2009, 09:48 PM   #5
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Should be fine. There are adapters made to do this.

John Wayne once said "Life is tough and it is even tougher if you are stupid"

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