Sending downspout water away

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djibouti33

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Sep 25, 2010
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Sacramento, CA
Hello,

I'm in the middle of a project to connect my downspouts to underground pipe to direct the water away from the house and towards the street, where the water will eventually spill out into the gutter and be taken away.

I'm planning on laying 1.5 inch pvc underground, and I was wondering if this will be large enough? I live in Sacramento, California, and we definitely get our share of rain, although I don't think we're breaking any records. According to wikipedia, we get about 21 inches per year, and it rains about 62 days out of the year.

I feel like 3 inch pipe would be overkill (and require me to pay more and go back and dig wider ditches) so I wanted to check here before I started putting everything together and burying the line.

Any suggestions or comments?

Thanks in advance!

Kevin
 
An overkill is far better than an underkill! I have eight 3" drain lines in my backyard, and when we get a few downpours, those are not enough to handle the run off. The amount of digging will be minimal, and the costs for the pipe are virtually the same.
 
I think 1 1/2" is a bit small and is asking for a clog. I did exactly what you are doing using 3" corrugated and have had no difficulties with carrying capacity or clogging.
FWIW
YMMV
 
What you are not realizing is that all the water from the roof is being channeled through/to 3 or 4" down spouts. A 1/4" of rain will back up in an 1-1/2" pipe.
 
Thanks everybody. Definitely compelling reasons to go with a 3 inch pipe. Back to the hardware store it is!

Would you recommend PVC or corrugated flexible? One line will be traveling through an area with almost no roots, whereas the other line goes through a ton of them (even though it's below most of them). Any preferences?
 
If your intention is to just divert the water away from the home, but not go into a storm drain or other suitable drain, and your yard consists of a nice sandy soil with good drainage, at a lower elevation than your home, you could use perforated flexible line. If you are draining to a storm drain, use solid PVC and glue it up good to avoid root intrusion.
 
Corrogated pipe is bad news if you have any shrubbery or trees that have roots . They will find thier way into the drain. I have one drain in my back yard. The original owner installed a 1-1/4" pvc drain from the back of my house under the concrete driveway They connected a 3" drain to that. When it rains all the water in my back yard goes into that drain. It can handle even the hardest rain. But it's not reccommended
I agree, a glued PVC the best choice
 

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