DIY Underground Downspout Drain

Hey friends! My husband has been saying he wants to bury the downspouts on the side of our garage for a few years now and he finally found the time to do it earlier this month. He took some photos, so I thought I’d share in case you want to bury your downspouts too!

Neither of us thought to take before photos, so here is a cute pic of my daughter last winter with the piece of corrugated pipe we always tripped over on our downspout. We have parking next to our garage, so we walked over and around this pipe a lot.

The process to bury these is pretty simple - dig a trench to lay pipe that connect to each downspout.

My husband works for an excavating company, so he brought home a mini excavator to do most of the digging. This is an in-process photo, but you can see how he dug the top layer of stone off of our driveway first with the mini excavator (approx 4”-6” deep) and then he hand dug the sand underneath (another 4”-6” deep) along the side of the garage for the pipe.

He kept each material (stone and sand) in separate piles, so that he could just shovel the first pile back in (sand) and then the second pile over top (stone) without having to haul in new material.

The pipe he used is SDR 35 PVC pipe in 4” diameter, which is the green pipe pictured.

To connect each piece of pipe, he used PVC primer and glue. The outside of the inside pipe and the inside of the outside pipe each get primer followed by glue.

To connect the gutter downspouts to the PVC pipe, he used 4” downspout adapters. They just slide over the metal spouts and clip inside the pipe - no glue needed.

Since we were connecting two downspouts (one from the front and one from the back of our garage), he used a 4” Wye to connect them to a single pipe that he ran into our yard.

The trench needs to be deeper from end to start for drainage fall, so he checked each piece of pipe with a level to make sure each end of pipe was lower than the pipe it was connected to.

Once the trench was filled, he used a rake to smooth everything.

He used a sawzall to cut the pipe that runs into our yard.

We dumped a bucket of water into the gutter to see if the dirt was just going to wash away, so then we decided we needed some stone around the pipe.

We put some weed barrier down first.

Then we used 2” stone under and around the pipe.

The cut pipe looked kind of unfinished sticking out, so my husband used his angle grinder with a wire wheel on it to shave down the top of the pipe.

We found a water line for our irrigation that we capped off years ago when we added parking next to the garage, so we pulled that up to add a sprinkler head to this area.

The last thing he did was put some pieces of cardboard between the downspouts and the house and spray paint the black adapters and green pipe white!