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How to Install a Dry Well and Divert Rain Run-Off

Controlling rain run-off with This Old House landscape contractor Roger Cook

In this video, This Old House landscape contractor Roger Cook controls rain run-off.


1. Lay out lengths of 4-inch-diameter PVC pipe from the end of the downspout out to the dry-well location. Start with two 10-foot lengths of standard pipe, then lay out two 10-foot lengths of perforated pipe.

2. Dig along each side of the standard pipe. Cut into the soil about 2 inches from either side of the pipe.

3. Upon reaching the perforated pipe dig into the soil about 6 inches from either side of the pipe.

4. Move the pipes aside and dig a 6- to 8-inch-deep trench.

5. Set the standard pipes into the trench and use a 4-foot level to ensure they pitch about ¼ inch per foot toward the dry well.

6. Line the remainder of the trench with landscape fabric, then cover the fabric with about 2 inches of stone.

7. Set the perforated pipe on top of the stone, add more stone, then wrap the landscape fabric around the pipe.

8. Connect the standard PVC pipe to the end of the downspout with a PVC 90 degree elbow and downspout adapter fitting.

9. Backfill around all pipes with soil dug from the trenches.

10. At the end of the perforated pipe, dig a hole for the dry well that's approximately three times wider and deeper than the dry well.

11. Line the dry-well hole with landscape fabric, then pour 4 to 6 inches of stone into the bottom of the hole. Spread the stone level.

12. Place the dry well in the hole, making sure the end of the perforated pipe extends into the dry well.

13. Backfill around the dry well with stone.

14. Set the plastic cover onto the dry well and tap it down with a rubber mallet.

15. Install a pop-up valve into the dry-well cover.

16. Cover the dry well with soil, making sure you don't bury the pop-up valve.

17. Rake the area over the dry well level, then plant grass seed.