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How to Install Downspout Drain Lines

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What happens to the water on the roof when it rains or snows heavily? You have gutters to channelize this water into the ground through downspouts. Now, you have a fresh problem on hand. The water from the downspouts can collect on the lawns or the backyard of the house thereby making it soggy. This can affect the foundation of the house. One way to avoid this problem is to have a series of underground drainpipes to siphon off the water far away from the house.

Install Downspout Drain Lines

Aim: To install downspout drain lines from draining rainwater

Materials Needed:

      • PVC drainage pipes
      • PVC elbows (recommended one for max. pressure)
      • T-fittings
      • Adapters
      • Couplings
      • Cement
      • Primer
      • Trench digging material. ( Lightweight and Portable)

Procedure: We shall distribute the work in three different phases.

Installing Downspout Drain Lines

  • Have a neat plan in mind. Using a string and stakes, lay out the trench
  • Sprinkle chalk powder or flour along the string to mark out the areas where you need to dig. Remove the strings now and place cardboards along the edges of the markings.
  • Start digging the trench and dump the earth on the cardboards. They can be very useful while backfilling the trenches.

underground downspout drain

  • It is better to have the trench around 6 inches wide. Ensure that it slopes down a gradient of 1 to 2 inches per length of pipe.
  • Alternatively, you can use a trench digging machine if it is rocky soil. A professional can do this job father that you can.
  • Depending on the climate of the area you live in, estimate the depth of the trench. Under normal circumstances, a 10 inch depth should be enough. If you live in areas where it snows a lot, it is better to dig a trench 36 to 46 inches deep.

Downspout to Drain Pipe

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  • Place the pipes beside the trench. This is to ensure you have all the parts ready for installation.
  • Press a downspout adapter inside a 3X4-inch reducer. Slip it into the downspout at the bottom end.
  • Place a 90-degree elbow directly below the downspout into the trench and measure the distance between the ends of the elbow and the coupling.
  • Cut a piece of PVC pipe according to slip it in between. Use primer and PVC cement to attach the pipe to the elbow. Hold them tight while giving a small twist. The cement will cure very quickly.
  • Insert the downspout adapter and reducer into this pipe gently. Go to the first turn and place a 90-degree elbow.
  • Cut the PVC pipe after measuring the distance and insert the same into these two elbows.
  • Continue with the installation until you reach the second downspout.
  • Repeat the same process of installing the adapter and reducer assembly at the second downspout.
  • Use a T fitting to connect the pipe from the downspout to the main pipeline.
  • Proceed with the same methods at every downspout. Wherever you need an elbow, use one. This will ensure that you finish the laying of the pipelines in an orderly fashion.
  • Ensure that the pipes slope down gradually. You can use couplings wherever necessary.
  • Use flexible PVC pipes where you encounter tough rocks. You may have to use a 3X4-inch reducer to glue the flexible pipes to the rigid ones.

Backfilling the Soil

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  • Check out if the entire job is over. You should not leave any downspout unattended.
  • Glue all the couplings and joints to ensure there is no leakage.
  • At the concluding point, dig a small pit, around 3 feet in diameter. Line it up with gravel and small stones. Lay the ends of your pipe on this rocky bed and place more gravel on it. Cover the pit with soil.
  • Before starting with the backfilling, it is better to test out your drain lines.
  • Pour water from the rooftops onto the gutters and check out where the water ends up.
  • This will also help you to identify leakages. Check out the gradients properly. The flow should be even.
  • You have the soil ready on the cardboards that you had kept at the time of digging. Cover the trenches with this soil and level the ground above.


Final Thoughts:

You have installed your drain lines perfectly. In fact, you have created a mini-rain water harvesting system in your house. You can recharge the groundwater supply using this system.


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