Rain Barrels: A Partial Solution?

How do you like my new rain barrel setup? Not bad, right?

Now picture this: During yesterday’s downpour, water was shooting out the downspout into the rain barrel on the right. Within a couple of minutes, the barrel was overflowing, splooshing old stagnant water out the top and sides.

As I tried to figure out the problem, I got drenched in a funky mix of fermenting leaf material and rooftop gunk. I smelled like I’d gone swimming in a swamp!

To explain how I ended up feeling (and looking) like a drowned rat, let me back up a little…

Free Rain Barrels!

Last April, I noticed a post on Nextdoor for free rain barrels. Sounded like a good deal. I’d been planning to set up rain barrels to reduce runoff in my backyard. I noticed the MWRD had been pushing rain barrels to help keep rainwater out of water reclamation plants during storms. Plus, I’m a dedicated do-it-yourselfer.

So I eagerly drove over to the donor’s house and picked up two rain barrels.

The First Uh-Oh

I should have known it wasn’t going to be a simple project.

While collecting tools and parts for installation, I went to a garden store and asked for a hose to handle overflow.

“I’ve got a rain barrel at home,” the salesperson told me, “and it’s set up to drain all the time. In this area, rainstorms are severe and unpredictable. Your rain barrel will always need to be drained empty, ready to deal with each new storm.”

Hmm… for some reason, I decided to set up both rain barrels at the critical downspout. One would be a receptacle. It would connect to the second barrel, which would handle overflow. The second barrel would drain continuously out the spigot, through a hose, into the front yard.

I also starting reading installation directions online. Installers recommended elevating the barrels, so water would flow out faster through the spigot when watering plants. And the downspout would need to be switched out for a shorter version, so it would be at the right position to pour into the top of the barrel.

The Second Uh-Oh

Once I’d assembled everything, I decided to run some numbers to get myself psyched up for the installation.

To determine the reduction in backyard flooding, I used these calculations:

Total area of the first floor rooftop, drained by the downspout:
20f x 30f = 600sf / 2 downspouts = 300sf

Inches of water during a storm (like last July):
6″ = .5f

Cubic feet of water to be drained:
300sf area x .5f depth = 150cf

Capacity of one of my rain barrels:
55gal each barrel

Turning to Google, I checked to see if 150cf fits in a 55 gal barrel:

Yikes! Not even close.

To handle 1122.08 gallons of runoff, I’d need 20.4 rain barrels. Even half that rainfall would require 10 rain barrels, just for one downspout.

Finishing the DIY Mission

I was discouraged, but in too deep to give up.

After a long afternoon, I managed the installation shown in the photo (above). This spring, the setup sort of worked, deflecting runoff into the barrels, and out to the front yard. Then yesterday’s storm occurred.

The first barrel, serving as the primary receptacle, was already full. In fact, it hadn’t been drained in weeks (hence the decaying rooftop fermentation).

When the storm hit, water gushed out the downspout like it was coming out of a firehose. The fill rate was too high for the overflow hose to handle. So I got drenched, as I struggled to figure out what was happening.

Final Thoughts

At this point, I’m doing what the garden store salesperson said to do. Both barrels are now empty, with the bottom spigots open and connected to hose for continuous draining, ready for the next storm. After cleaning out the barrels, I’ll try to figure out how to increase the overflow handling for the main barrel.

On the plus side, I now understand what I’ve heard so often the past couple years: Green infrastructure (like rain barrels) can only supplement, not replace, the far more necessary steps of 1) installing and maintaining adequate storm sewers and 2) maintaining as much permeable ground area as possible.


For more rain barrel installation advice:

For more information about why DIY green infrastructure can’t solve westside Wilmette’s stormwater issues:


  1. Kim June 16, 2017
  2. Joel Feinstein June 16, 2017

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