In the area behind my house, the ground slopes downward, creating a 2.5ft drop over a span of 12ft. After this slope, the terrain levels out for about 70ft until it reaches the property boundary.

Currently, the rainwater downspouts release water onto the sloped grassy area. However, the water running down the slope gradually erodes the soil, forming noticeable channels despite the presence of grass. This erosion makes it challenging to maintain a smooth surface.

To address this, I'm considering digging a trench and installing an underground drain pipe. This pipe would carry the water from the downspouts to a garden bed located at the far end of the property, ending with a popup emitter.

I'm anticipating a challenge: in order to maintain a 2% downward slope across the flat 70ft section of the yard, I'd need the pipe to have a drop of 17 inches. This would mean the pipe ends up being a few feet below grade.

Popup emitters I've found are designed for use with pipes that are closer to the surface. If I use a riser to get up to grade, should I expect issues?

For aesthetic reasons it's important to me that I avoid placing an emitter closer to the house.

  • 1
    Have you considered a level spreader at the downspout?
    – Huesmann
    Aug 21, 2023 at 16:35

1 Answer 1


If you provide a settling tank to remove debris ahead of them, you could run perforated pipes dead level across the flat area (as is done for a septic leach field.) You'd need to clean the debris out of the tank from time to time. That would percolate most of the water back into the ground, with any excess making it to your emitter.

Without a settling tank clogging is likely (probably even with a 2% slope) since any debris that gets to the end would have to be pushed up to the surface emitter, so it seems likely that some of it (the heavier stuff - granules from asphalt shingles, etc.) would gradually build up in the low part of the pipe there and eventually plug it. You could perhaps place a dry well there as a place for debris to collect and be removed at that end.

Since 2.5 feet in 12 feet is a rather steep slope, another option would be to haul in more dirt to make a gentler slope.

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