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How to Design a Rock Filled Gutter Drain Sump

A rock filled gutter drain sump is also called a dry well or weep pit. A properly designed and installed dry well is beneficial to remove water away from a building foundation to reduce water seepage into foundations and basements. A gutter drain sump is an effective way to move water from gutters away from the house.

Use a plastic trash can as a liner for the drain sump.
  1. Plan the location of the rock filled sump at least eight feet from the bottom of the downspout. Place a stake at the starting point. Measure at least eight feet from the stake and install another stake to mark the location for the edge of the dry well.

  2. Dig a trench from the bottom of the downspout to the location for the dry well. The trench must be at least eight inches deeper and wider than the width of the drainage pipe. The trench must slope at least one inch for every eight feet to provide adequate flow for water in the drainage pipe.

  3. Measure the width and height of the plastic trash can. Dig a round pit four inches deeper than the trash can is tall and at least as wide as the trash can.

  4. Place the edge of the drainage pipe against the side of the trash can approximately two inches from the top of the trash can. Use a marker to trace around the drainage pipe. Cut the circle out of the can with a utility knife. Drill many holes in the sides and bottom of the trash can with a ¾-inch drill bit. Place the trash can into the hole with the circle for the drainage pipe facing toward the trench.

  5. Tie a string around the stake at the starting point, pull it tight and tie the other end to the stake at the edge of the dry well. Place a line level on the string to ensure that the string is level.

  6. Measure the distance from the string to the bottom of the trench close to the downspout. Measure the distance from the string to the bottom of the opening for the drainage pipe on the trash can. Measure the length of the string and divide by eight. The difference between the distance from the first two measurements must be at least the result from dividing the length of the string by eight. For example, if the trench is 16 feet long, the result is two inches. If the measurement from the string to the bottom of the trench next to the downspout is 15 inches, the measurement from the string to the drainage pipe opening on the trash can must be at least 17 inches. Make adjustments in the depth of the trench and the depth of the trash can so proper slope is achieved.

  7. Remove the trash can and line the pit and trench with landscaping fabric. Center the landscaping fabric in the trench with the sides of the fabric against the walls of the trench. Place the trash can back in the hole.

  8. Fill the trench with two inches of gravel.

  9. Place the drainage pipe in the trench. Place the downspout connection on the end of the drainage pipe a move into position directly under the downspout. Insert the other end of the drainage pipe into the hole in the trash can so at least two inches of the pipe is in the trash can. Connect sections of pipe if needed.

  10. Remove the elbow at the base of the downspout by removing screws, drilling out the rivets with a 1/8-inch drill bit placed in the center of the rivet, or cutting with a hacksaw. Measure the distance between the bottom of the downspout to the downspout connection on the drainage pipe. Cut a section of downspout using this measurement and attach to the bottom of the existing downspout. Position the bottom end in the downspout connection on the drainage pipe. Drill pilot holes with a 1/8-inch drill bit through each while in position on both sides and the front and install rivets or short sheet metal screws in each hole.

  11. Cover the pipe in the trench with approximately two inches of gravel and fold the sides of the landscaping fabric over the gravel. Fill the trash can with larger stones and top of the can with a thick layer of gravel. Place a double layer of landscaping fabric over the top of the trash can.

  12. Replace soil and sod in the trench and over the trash can so it is level with the surrounding landscape.

Warning

  • Call your local municipal office to check for possible underground utilities before beginning this project.

About the Author

Emily Patterson has been creating content for websites since 1996. She specializes in home improvement, natural body care and natural cleaning articles. Patterson holds a computing certificate from Penn State University.