You finally installed a rain barrel… and then the first storm hit.
At first, it was thrilling—watching that water pour off the roof and into the barrel like you'd just unlocked nature’s secret faucet. But by hour two of a heavy rain, the excitement faded fast. The barrel filled to the brim, water started spilling over the sides, and before you knew it, there was a muddy moat forming around your foundation.
Not exactly the eco-friendly win you were hoping for.
Trust me, I’ve been there. That was me back in 2005, soaking wet in the middle of a thunderstorm, watching water gush out the top of my first homemade rain barrel. I repurposed a rain barrel and stuck it under the gutter. What more did I need to do?
No one mentioned the part where it overflows like a fire hydrant. That soggy disaster was my wake-up call.
A diverter is what makes the whole system work like it should, automatically redirecting water into the barrel when there’s room and sending it safely away when it’s full. Without it, you're left with standing water, soggy soil, and a whole lot of regret.
Let’s make sure your rain barrel setup doesn’t just look smart—it works smart.
What Is a Rain Barrel Diverter?
A rain barrel diverter is a device that attaches to your downspout and acts as a traffic cop for rainwater.
When it rains, the diverter redirects water from your gutters into your barrel. Once the barrel is full, it automatically reroutes the excess water back down the downspout, safely away from your home’s foundation. It’s a smart, hands-off way to keep your barrel full—but not too full.
A lot of folks think you can plop a barrel under a downspout and call it a day. That’s what I did when I started, and it worked… until it didn’t. Without a diverter, that setup is basically a bucket under a waterfall. Once it fills up, water keeps coming, spills over, erodes your soil, floods your mulch, and if you're really unlucky, starts seeping into your basement.
A spigot might help you use the water, but it does nothing to manage the inflow. A diverter, on the other hand, controls the whole traffic pattern—from entry to overflow—and does it automatically if you set it up right.
If you’re serious about harvesting rainwater without creating a drainage nightmare, a diverter isn’t optional—it’s the backbone of your whole system.
How Does a Downspoutt Barrel Diverter Work? (Step-by-Step Breakdown)
Let’s break it down. A rain barrel diverter is deceptively simple, but what’s happening inside that little piece of hardware is surprisingly smart.
Step 1: Rainwater Enters from the Downspout
When it starts to rain, water flows from your roof into the gutters and down the vertical downspout. That’s where the diverter lives—right in the path of that flowing water. You either cut the downspout and insert the diverter (most common), or, in some setups, drill a hole and tap into it with a fitting.
Step 2: Gravity and Surface Tension Take Over
Here’s the cool part—physics does most of the work. Rainwater hugs the inner walls of the downspout as it falls. The diverter takes advantage of this surface tension, guiding water through a channel or spout into a hose connected to the barrel. There's no pump. No pressure system. Just good ol’ gravity doing its job.
But here's the kicker: if your diverter is too high, or your hose dips uphill at any point, you’ll get a trickle—or nothing at all. That’s one of the most common setup mistakes I see. The water needs a smooth, downward path.
Step 3: Water Fills the Barrel
The water flows into the barrel through a sealed inlet—usually a hose or PVC pipe that enters through a watertight grommet or bulkhead fitting. As long as the barrel has room, water keeps flowing in. It's clean, collected, and ready for use.
Step 4: What Happens When the Barrel Is Full?
Once the barrel reaches capacity, a good diverter kicks into phase two: overflow redirection.
Here’s what happens depending on the diverter:
Automatic Diverters: These often have an internal float or a level sensor. Once the water level in the barrel hits the limit, the diverter stops sending water into the barrel and redirects it down the downspout or into an overflow pipe.
Manual Diverters: These require you to flip a lever or cap to switch water flow manually. They work great if you like having control or if you’re using the diverter seasonally.
Without a diverter—or if you use just a basic open-top barrel? Yup, you’ll overflow. And yes, that means water pouring over the edges, right back toward your foundation, garden beds, or mulch. Been there. Fixed that.
Do You Really Need a Diverter for a Rain Barrel?
Yes… Unless you enjoy foundation repairs and standing water.
I've talked to hundreds—probably thousands—of homeowners over the years who thought a rain barrel was just “stick it under the gutter and wait.” It’s not. And if you go without a diverter, you’re setting yourself up for a mess.
Let’s break it down:
Without a Diverter
Overflow Happens Fast: Most barrels fill up in the first 30 minutes of a decent storm. Without a diverter, the excess has nowhere to go.
Risk of Foundation Damage: That overflow pours down the side of your barrel and pools next to your foundation. Water + time = structural problems.
Mosquito Magnet: Stagnant overflow creates the perfect breeding ground.
Zero Control: You either babysit your barrel or let it flood. No middle ground.
Ugly Workarounds: People start punching holes and running weird tubes just to drain excess—none of it efficient or safe.
With a Diverter
Automatic Overflow Control: The diverter reroutes water safely away once the barrel is full.
Cleaner Setup: Closed, sealed, and low maintenance.
Better Water Quality: Leaf screens and enclosed systems reduce debris and contamination.
Protects Gutter System: If your barrel overflows back up into the downspout, it can cause blockages. Diverters prevent that.
Set-and-Forget Convenience: Especially with automatic models, the system manages itself through storms and seasons.
How to Install a Downspout Barrel Diverter
Installing a diverter isn’t rocket science—but it’s also not slap-it-on-and-hope-for-the-best. Over the past 20 years, I’ve seen every mistake in the book. So let’s walk through how to do it the right way, with a few tricks I’ve picked up that’ll save you frustration (and maybe your siding).
Tools You’ll Need:
A drill with hole saw or paddle bit (usually 1?"–1½")
Measuring tape
Marker or pencil
Hacksaw or tin snips (if cutting the downspout)
Screwdriver
Level (optional but helpful)
Caulk (for sealing, if needed)Gloves (because aluminum edges bite)
1. Pick Your Placement
Find a section of your downspout that’s:
Above the rain barrel
Easily accessible (not behind bushes or fences)
Not too high (a common mistake)
Tip: The diverter needs to sit above the barrel, but not too high—just enough for gravity to do its thing. Too high and the water loses momentum, leading to poor flow or total siphon failure.
2. Measure the Barrel Inlet Height
Mark the point on the downspout that's 2–3 inches above the barrel’s top. That’s your sweet spot for drilling or cutting.
Don’t eyeball this. I've had customers call me furious that their diverter “doesn’t work,” only to realize they installed it a foot too high.
3. Cut or Drill Into the Downspout
Cut-in diverters: Use a hacksaw to remove a section of the downspout and insert the diverter.
Drill-in diverters: Use a hole saw to punch a clean opening for the diverter hose or fitting.
Dry fit everything before tightening or sealing.
4. Insert Diverter and Hose
Feed the diverter hose from the downspout to your barrel. Make sure:
The hose slopes downward (no dips or loops).
The barrel inlet is sealed with a proper grommet or bulkhead fitting.
If you have to force it, something’s wrong. Water needs a free-flowing path.
5. Secure and Seal
Attach your diverter with included screws or brackets. If needed, apply a bead of exterior-grade caulk around the edges for a leak-tight seal.
How to Handle Overflow: What Happens When the Barrel Is Full?
Here’s the thing they don’t tell you in those cutesy rain barrel how-to videos: your barrel is going to fill up fast. A 1,000-square-foot roof can collect over 600 gallons from just an inch of rain. Most rain barrels? They max out around 50–65 gallons.
So… what happens next?
If you don’t have a proper overflow plan, the answer is: a big mess.
Internal Diverter Floats (Automatic Models)
Automatic diverters are the smart ones in the family. Inside the diverter, there’s a float or flap that rises with the water level in your barrel. Once it hits a preset point, the diverter senses there's no more room and redirects the flow back down the downspout or into an alternate path.
No touching. No switching. No soaked basement.
Great for folks who just want to set it and forget it.
Manual Toggles for High-Rain Seasons
If you're the kind of person who likes hands-on control (or if you don’t mind a little rain), a manual diverter lets you physically flip a switch or cap to change the water flow.
Pro Tip from Barry: In spring and fall when storms get wild, I leave my diverter in bypass mode until I’m ready to collect. Then I switch it back on when I know we’ll have a light rain.
Connecting Multiple Barrels (Daisy-Chaining)
One barrel is good. Two—or three—is better, especially during big storms.
There are two smart ways to expand:
Bottom-feed connector hose: Connect barrels at their lowest point so they fill evenly.
Dual-outlet diverter: Some diverters have a split channel to send overflow into a second or third barrel—or even into a garden hose for irrigation.
Mosquitoes, Debris, and Diverter Maintenance
Let’s talk about what happens after the rain.
A diverter isn’t just about redirecting water—it also plays a huge role in keeping your system clean, safe, and running smoothly. But here’s the catch: if you set it and forget it, nature will sneak in. Debris builds up, mosquitoes find standing water, and before you know it, your rain-saving dream smells like swamp soup.
Why Closed Diverters Keep Mosquitoes Out
One of the biggest advantages of using a diverter—especially a closed system like the ones we build at AquaBarrel—is that you’re limiting open water exposure. No open tops. No puddles. No access.
Mosquitoes love still water, and most rain barrel problems start with a simple mistake: forgetting to seal everything up tight. Our diverters use sealed hoses and fittings, keeping bugs on the outside looking in.
Fun fact: I’ve had folks call to thank me because our diverter design literally stopped a mosquito infestation in its tracks. That’s a win in my book.
Cleaning Screens and Filters (Yes, It’s Necessary)
Even the best diverter can get jammed up if you never clean it. Most quality diverters come with built-in screens or debris traps—and those need attention, especially during leaf season.
What to clean:
Leaf screens
Inlet filtersThe diverter’s internal chamber (flush it with a hose if accessible)
Barry’s Rule: Clean it every season—especially spring and fall. It takes five minutes and saves you hours of troubleshooting.
First Rainfall = Biggest Mess
That first downpour after a dry spell? It’s like someone tipped a bucket of roof gunk into your gutter. Twigs, pollen, shingle grit, bird nests—you name it. If you don’t check your diverter after that first storm, odds are it’s already clogged.
Pro Tip: Install a removable clean-out cap or access port if your diverter doesn’t have one. Makes your life way easier.
Add a Leaf Guard or Pre-Filter
Want to go the extra mile? Add a leaf guard or debris filter before the diverter. It’s like a first line of defense for your system. Stops the big stuff before it ever hits your diverter.
Is a Diverter Worth It?
Let me put it this way—if you’re serious about harvesting rainwater, protecting your home, and avoiding constant headaches, then yes, a diverter is absolutely worth it. I’ve seen what happens when people skip it, and I’ve also seen how a simple diverter can turn a chaotic, overflowing setup into a smooth, low-maintenance water-saving machine.
Choosing the right downspout diverter can make all the difference in how efficiently you collect and control rainwater.
Our Y-Only Rectangular Downspout Diverter gives you maximum flow control with its dual-output design—perfect for directing water to two different locations or toggling between a rain barrel and drainage.
The In-Line Downspout Diverter offers a clean, concealed look that installs directly inside your downspout, making it an excellent option for homeowners who want function without visible hardware.
For those with space constraints or offset barrels, the Downspout Diverter Off-Set is designed to create distance between your downspout and rain barrel while still capturing water effectively.
And if you’re in Canada or have a square downspout system, the Canada Square Pipe Diverter is tailored specifically for your unique setup—no adapters or awkward fittings required.
Each diverter is crafted to simplify your system and increase water harvesting potential. No matter your gutter style or rain barrel location, AquaBarrel has a diverter built to fit and perform.