Corrugated Drain Pipe; Simple, Right?

I need a 10-ft length of corrugated drain pipe (4-in diameter, typ. nominal). Both Lowes and Home Depot sell (a) a 10-ft length of “corrugated solid pipe” and 10-ft length of “corrugated perforated pipe” that sounds like what I need. But! Both have similar if not identical descriptions (where more details are provided).

Which do I want? I simply want a corrugated drain pipe with some flexibility to run rain water from the downspout away from the house. “Solid pipe” sounds rigid and “perforated” sounds like it full of holes, like a soaker hose*, maybe? Please advise. Thanks!

*Note: I am aware there is a roll-up, plastic material you can attach to the downspout that will unfurl when it rains, and this roll-up plastic material can be said to be perforated to act as a soaker hose. But, i strongly believe what I described above, based on the pictures on the respective retailers’ websites, do not appear to be referring to this style of downspout extension…
should not be referring to

You want solid. The corrugated pipe flexes, but it is still fairly rigid. The perforated type has a series of holes in it and is meant to let water in or out of the pipe, usually when it is sitting in a bed of gravel.

Yeah, you want solid. The perforated pipe is for installing underground “French drains”:

If you were to build a proper French drain you’d want a 5 feet of solid to carry the water away from the house followed by 10-20 feet of perforated to drain the water underground. And you’d be looking at trenching 15-25 feet across your lawn to a depth of 12-18", installing gravel, etc.

I’d be surprised if you really want 4" pipe leading away from a typical downspout. Assuming your grading is OK and you don’t live in a rainforest you just need to move the water 5 feet away from the downspout and let it go. Something smaller that connects properly to the downspout outlet is probably sufficent for that mission. Although there are adaptors that connect standard 4" corrugated drain pipe to standard ~1.5" x ~3" rectangular downspouts.

I appreciate your thoughts, LSL Guy. Our basement is always damp, so I’d like to be sure the water empties out past where the basement wall ends (and down a slight slope). We are not the original owners of this house, and we would come to learn the land could have been graded better and/or the basement waterproofing was NOT a quality job.

This particular downspout actually has an existing corrugated pipe someone ran underground, under a flower bed (actually, it’s more than just flowers as it has a mature azalea and other mature foliage) with the outlet exposed at the bottom of this sloped mound of a flower bed (if you can picture this). However, over time, the downspout fell off the house. The handiman who reinstalled it did not align it with the existing corrugated pipe inlet (and I forgot to mention it to him until it was too late).

I don’t know how the drainpipe was supported before to align properly, but now it sits higher than the inlet to the corrugated pipe. I imagine it would take some kind of a gooseneck piece of drainpipe to employ the existing corrugated pipe. Thus, it’d be easier for me to run a new piece of corrugated pipe above ground. The slope of the back of the mound (practically against the house exterior wall in a straight line with this drainpipe which comes off a front porch overhang just a few feet offset from the house exterior wall) will still be adequate to carry the water away from the house without having to disturb the established flower bed.

Hmm, on second thought, maybe I could spot tie (zip tie) a funnel from Walmart automotive with a 2-in diameter gooseneck flex pipe for an outlet???

Thanks to all for the explanation. While I’ve seen these pipes sitting in a Lowes or Home Depot, I never knew there are actually two different types of corrugated pipe.

^Referring back to the end of my reply to LSL Guy: Another off-the-cuff thought is maybe I can cut a gallon milk jug into a funnel or use it as a makeshift splashboard to guide the water into the existing corrugated pipe. Hmm…

This. Rather that Rube Goldberging something from a milk jug, the hardware store sells flexible corrugated sections of downspout that you can bend into any sort of S you need to connect to the existing misaligned pipe.

^^ this.

→ this:

If you use a corrugated pipe to extend your downspout, you’ll be creating a chain of standing water pools inside the pipe for a few days after every rain. That’s long enough to breed many thousands of mosquitoes right next to your house. That’s a side effect you might regret. Use the smooth pipe. You did mean the crossways corrugations, right?