Material for underground drainage


Old 05-30-13, 04:01 PM
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Material for underground drainage

Installing some underground drainage for two downspouts. Just looking to re-route the water and am planning on having a "pop-up" at the end of the run.

Which material should I use for the piping? I assume PVC is the best, but is costly. The corrugated is cheaper, but some people say not to use it? I understand the porous corrugated can collapse easily. Is it the same for the solid?

SO, in a nutshell, PVC or corrugated for underground re-routing of water?
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Old 05-30-13, 08:06 PM
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PVC has to be pitched perfectly so without knowing the rest of the details, I vote for corrugated.
Old 05-30-13, 08:43 PM
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PVC should be pitched or can even work flat since water seeks its own level (down the pipe) to the lowest point.

Corrugated (flexible) will usually have dips and low areas the collect even more dirt/silt/etc.

If you are talking about perforated, then the corrugated will have more debris than PVC if both are installed properly. Of course, perforated is only used for collection. Solid wall piping is what performs best to get water somewhere else. Some people will use solid wall pipe and then switch to perforated when they get fat enough away (vertical or horizontal) and then use perforated for gradual distribution instead of pop-ups that can freeze quickly before the ground below.

I had a single large downspout (long gutter runs) and the extra flow capacity of PVC vs, corrugated was enough because of the large flow. The installer avoids corrugated because we are in a cold climate and a smooth flow reduces freezing problems, but our pop-up gets a beating and almost becomes air-borne in a good storm.

Old 05-31-13, 12:55 AM
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ALL drainage lines need to be pitched toward the outlet. If you want to use flexible (corrugated) piping then stick a 2x4 in it to make it straight as you lay the pipe. Remove the 2x4 before coupling the next piece.

Personally, I would use either rigid PVC or ABS.
Old 05-31-13, 04:20 AM
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Thanks everyone!

I was leaning towards PVC already.

A few more questions...

I assume I should go with 4" for the added capacity (two downspouts will feed it)?

Do you advocate drilling a hole in the bottom of the pipe at the end of the run to allow excess water to drain out into the ground (to avoid freezing in the winter)?

How did you connect your downspouts to the pipe? I've seen a few different options: downspout slips inside PVC sticking up about 3 feet above ground; a flexible adapter between the ds and the pipe; or a "kit" where there's an air gap between the ds and a screen-covered box.

My concern is being able to clean out debris from the pipe...

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