How to install an underground gutter drainage

Updated February 21, 2017

Gutter downspouts empty water several inches from the foundation of the house. If the ground next to the foundation does not slope away from the house, the water pools and seeps into the ground. Water-saturated ground next to a foundation can cause structural damage that may require costly repairs. One solution to prevent water from soaking into the ground after it comes out of the downspout is a pipe running from the downspout to the curb gutter.

Excavate a trench with a pickaxe or a trencher from the downspout to the curb. Dig the trench 7 inches deep to allow for 3 inches of cover over your pipe after you backfill. The slope must be at least 1/8 inch per foot from the house. Smooth the bottom of the trench with a rake, place the level at the bottom and check the rate of fall indicator in the bubble window. A steeper slope is acceptable, but the pipe will not drain with a shallower slope.

Slide the downspout adaptor over the end of the downspout and fasten it with a poly pipe clamp. Slide the first section of PVC pipe into the downspout adaptor, clamp it and lay it in the trench. Glue a coupler to the other end of the pipe and glue another section of pipe to the coupler. Add sections and couplers until you reach the curb. If you need to make a turn with your tile to reach the curb, use 45-degree fittings. If you must make a 90-degree turn, couple two 45-degree fittings to prevent debris from creating a clog.

Drill a hole through the back of the curb with the concrete core drill. Drill the hole at the same angle the pipe is falling. Saw a section of pipe that reaches from the last pipe laid in the trench to the front of the curb. Slide the pipe into the hole and push it several inches past the front of the curb. Pull the pipe back toward the house and glue it to the last coupler you fit on the pipe in the trench. Bury the pipe by filling the trench with dirt.


Before drilling through the curb, notify the municipal building and planning department. If they are not comfortable with you drilling the hole, most likely they will offer to do it for you.

Things You'll Need

  • Pickaxe or trencher
  • Downspout adaptor
  • Poly pipe clamps
  • 4-inch PVC pipes
  • 4-inch PVC couplers
  • 4-inch 45-degree couplers
  • PVC primer and glue
  • Level
  • Concrete core drill or rotary hammer drill
  • 4-inch drill bit
  • Pipe saw
  • Rake
  • Shovel
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