I noticed a few weeks ago during the rainy season that underground drainage from my downspout was flooded and not draining right. I purchased a pressure washer attachment that promised to unclog things like this and went to town.

I could hear it underground and after being stuck at the same distance for a while I decided to start digging at that spot. I found a elbow pointing up and a green attachment. My guess is it's supposed to be above ground, and just got buried from years of neglect; I didn't know it and have owned the house for several years.

What is the correct way to reinstall this so it drains properly?

Running a pressure washer attachment through the drain:

enter image description here

After about 20 minutes of trying to snake it around a corner I decided to dig and found this:

enter image description here

The device attached the PVC elbow appears to pop up as needed:

enter image description here

  • Is the end point far away from the house, and is it lower?
    – MikeB
    Commented May 15, 2023 at 15:25
  • @MikeB It's reasonably far away, about 10ft, but it's not actually much lower. I'm going to be looking into extending the pipe to a lower location, but that would require bends to keep it on my property -- so I'll have to look into that.
    – Sidney
    Commented May 15, 2023 at 15:28
  • Do you have a conventional stormwater drain anywhere? That seems awful close to your house. Personally I'd run it much further down the grade AND off at an angle, so it is not "below" a building. Even all the way to the nearest creek could be better than there eroding your slope.
    – Criggie
    Commented May 17, 2023 at 2:24
  • 1
    @Criggie I'm actually considering doing that as a summer project. See the linked question to this one -- these holes are all over my yard with no rhyme or reason -- I'm going to set up 2 common paths one to the steet and one to the lowest point on my property line which should lead to a runoff ditch.
    – Sidney
    Commented May 17, 2023 at 19:20

2 Answers 2


The green part is supposed to be flush with the bottom of the blades of grass. This so the lawn can be mowed without having to go around the drain.

The center of the drain is pushed up by water. There is no spring or other device. It is strictly a passive process that relies on the rain water building up behind it enough to push the center up and allow the water out of the drain line. Because of this design, the device needs to be installed far enough away and lower than the grade at the house to allow gravity to work and water to flow away through the drain line terminating at the "pop-up".

Obviously, the termination point needs to be lower than at the home so the water doesn't flow back toward the house. Because of this and other factors, (such as amount of rain collected in the gutter serviced by the down spout) sometimes the corrugated piping does not work well and solid drain piping is needed run to the pop-up.

Now a simple thing became complicated, but once set up correctly, it will move water away from the home very well. Good Luck


RMDman is spot on, but there's a critical component missing in your system which may have contributed to the problem: A debris filter grate.

You'll notice that most diagrams for this sort of thing show something between the downspout and the underground pipe intended to slough off debris. Any larger debris that enters the pipe is likely to catch on the corrugations of your flex pipe or settle to the bottom, or it may snag on the smaller popup opening.

enter image description here


  • Interestingly enough a handful of pipes I've looked at appear to be filled with a fine sand (looks like it might be material from my roof?); I'm going to look into using a vacuum of some kind to help extract all that sand. Would PVC pipe make this cleanout process easier? I don't want to -- but if I need to replace the corrugated pipe is PVC a better option?
    – Sidney
    Commented May 15, 2023 at 15:33
  • PVC would probably help, but silt can't easily be completely resolved. It may take annual cleanouts.
    – isherwood
    Commented May 15, 2023 at 15:36
  • 3
    My only caution would be shifting ground. I see your cement shifting a bit already. Here in Colorado we have areas with extensively shifting soil. I had to replace a PVC drain with the flexible pipe as the PVC had shattered and became useless.
    – stdunbar
    Commented May 15, 2023 at 19:42
  • 1
    Yeah, especially in freezing climates.
    – isherwood
    Commented May 15, 2023 at 20:04

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.