How to Connect a Rain Barrel to a Downspout
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How to connect a water barrel to downspout comes down to three jobs: a level base close to the downspout, a diverter hole cut into the downspout at the right height, and a hose that runs from the diverter to the barrel without sagging. The Penn State Extension construction guide, the Colorado State University water center installation guide and the Las Virgenes Municipal Water District steps agree on the order, and they differ on a few measurements, which we point out.
The steps below follow that order from the ground up.
Quick answer
- Set the barrel on a level, firm base within about three feet of the downspout.
- Mark the diverter hole with a level so the diverter sits at the height of the barrel’s fill hole.
- Fit the diverter, connect the hose and check that the diverter tube is level with the intake hole.
- Plan the overflow so that water leaves the barrel away from the house, and inspect the fittings regularly.
Gather the parts and tools before you cut
The guides list a short set of tools. Penn State uses a hole saw for each opening, a drill, a level, screws for the diverter and a hose for the connection. Colorado State also uses hole saws, and the Las Virgenes page adds a hacksaw for cutting the downspout and elbows for any offset. Check your kit against your barrel before you drill, and follow the kit’s own instructions for hole sizes where they differ from the guides.
Two safety points come from the guides. The Colorado State page warns: “Always wear eye protection and gloves when drilling into metal”. That warning is written for metal barrels and downspouts, but the same care applies to any drilling. The Las Virgenes page says the downspout will likely need to be shortened, which means cutting it, so plan that cut before the diverter goes in.
Pick the spot and level the base
Placement decides how easy the rest of the job is. Penn State gives two rules: “Make sure the ground is level and firm.” and “Keep the barrel within three feet of the downspout.” The Las Virgenes page starts with the same idea in other words: “Find a location near a rain gutter down spout.” It also says to “Look for places where water can overflow from the rain barrel and be diverted to your garden.”
Level the ground before you raise the barrel. Penn State says to “Use sand or gravel to help level the area.” The Las Virgenes page recommends using “a level to prepare the ground and to align the base” so the barrel stands stable. The same page gives a reason to raise the barrel: its guidance is to “allow gravity to assist your irrigation with saved water”, which means a barrel set on a base lets water flow out of the spigot more easily.
Penn State raises the barrel on a block: “Elevate the barrel on a cinder block or bricks.” Check the level once the barrel is on its base.
Mark the spigot and the fill hole
The barrel has two holes to make: a spigot near the bottom for taking water out, and a fill hole near the top that takes the diverter hose. The two guides agree on the fill hole and differ on the spigot.
For the fill hole, Penn State says to “Go to the opposite side of the barrel and measure down three inches from the top and mark that spot.” The Colorado State guide sets the same height for its fill hole: “Measure down 3 inches from the top of the barrel, make a mark with a pencil.” Colorado adds that “The hole should be on the side of the barrel closest to the downspout”, which is the side where the hose will run.
For the spigot, the two guides give different heights. Penn State says to “measure up ten inches from the bottom” for the spigot. Colorado State’s steps put the spigot at 3 inches from the bottom. The table below sets both figures side by side, so you can choose the height that fits your own use.
| Item | Penn State Extension | Colorado State water center | Las Virgenes Municipal Water District |
|---|---|---|---|
| Barrel distance from downspout | Within three feet | Not stated | Near a rain gutter downspout |
| Spigot height | Ten inches up from the bottom | 3 inches up from the bottom | Not stated |
| Fill hole height | Three inches down from the top | 3 inches down from the top | Not stated |
| Diverter hole size | Large 2 1/8-inch hole saw | Not stated | No diverter; downspout cut and elbows added |
| Overflow | Not stated | Plan for overflow and direct it away from the house | Divert overflow to the garden |
The table shows where the sources disagree. Penn State and Colorado State both put the fill hole at 3 inches from the top, which is a clear shared figure. The spigot figures conflict, so the choice is yours: a higher spigot leaves less stored water below the outlet, and Colorado warns about that directly. “Once the water level falls below the spigot, you would not able to draw water out of the barrel.”
Cut the diverter hole in the downspout
The diverter goes into the downspout, and its height must match the fill hole. Penn State’s method starts with the barrel in place: “Lay your level across the top of the barrel toward the downspout and mark a dot on the center of the downspout.” Make the mark only after the barrel sits on its base, because the mark depends on that height.
Colorado State gives the same idea as a rule for the diverter itself: “The tube MUST BE LEVEL with the intake hole to allow water to flow back out the downspout.” Use the level to carry the height of the fill hole onto the downspout, and mark the spot. If the downspout is too long for the barrel, the Las Virgenes page says to cut it “using a hacksaw” and attach the elbows.
Penn State drills the mark with a large hole saw: “Using the large, 2 1/8-inch hole saw, drill a hole in the downspout at the spot marked.”
Install the diverter
Fit the diverter by squeezing its sides and pushing it into the hole. Penn State gives the orientation: “Make sure that the cup part is facing upwards, and the diverter does not get twisted.”
Then fix it in place. Penn State says to “Screw the two screws into the holes in the downspout diverter to hold it in place.” Use the screws that come with the kit. The guide does not name a size, so the kit’s instructions govern.
Connect the hose to the barrel
The hose carries water from the diverter to the barrel’s fill hole. Penn State gives the steps: “Connect the fill hose to the end of the downspout diverter and press it in firmly.” and “Connect the other end of the hose to the water inlet on the barrel and press it in firmly.”
Length is the adjustment point. Penn State notes: “The hose can be cut if needed to shorten the length.” Keep the hose run in view while you work, so the diverter tube can be checked against the intake hole as described above.
Plan the overflow
A full barrel needs a way out. Colorado State says: “Plan to use water to avoid overflow.” Its advice is to plan the overflow path before you fill the barrel: “If your barrel has an overflow valve, direct it away from your house or flood-prone areas.” It also gives a useful outlet: “Overflow water can be directed toward your lawn or garden.”
The Las Virgenes page agrees on the destination: look for “places where water can overflow from the rain barrel and be diverted to your garden.”
Check the setup with a run of water
Before you rely on the setup, run water through it. The Las Virgenes page gives the check: “Run some water through your gutters with a hose into the rain barrel to check for any issues.” Watch the diverter, the hose and the joints while the water runs, and look for drips or a loose fit.
Penn State adds a longer-term habit: “Inspect the barrel regularly for any leaks.” A leak at a joint is easy to fix when it is found early, so make the inspection part of the spring routine.
Keep the barrel clean and closed
The Colorado State guide warns about the mesh you put over the openings: “Beware using screens with large holes as they may not keep insects or particulates out of your rain barrel.” Choose a fine screen for the fill point. Keeping debris out protects the water and the spigot.
The same guide also warns about standing water in certain barrel designs. For one design it notes that an unplanted depression “will accumulate water and create a mosquito breeding ground”. The page’s fix for that design is to fill the depression with a plant.
Winter and the downspout
Winter changes the picture. The Colorado State guide says that one design “will be more difficult to winterize because you will need to add on a downspout extender to ensure melt water does not pour onto your foundation in the winter months”. The concern there is the foundation, so plan the overflow route and any downspout extender before the first freeze.
The sources we opened do not describe a full winter shutdown for a diverter system. They do not say whether the barrel should be drained, emptied or left in place through a freeze, so check your barrel’s instructions and your local practice before the cold arrives.
Mistakes to avoid
- Setting the barrel on uneven ground. Penn State says the ground must be level and firm.
- Mounting the barrel too far from the downspout. Penn State gives three feet as the limit.
- Letting the diverter twist. Penn State says the cup should face up and the diverter should not twist.
- Leaving the diverter tube out of level. The Colorado State guide says the tube must be level with the intake hole.
- Skipping the overflow plan. Colorado State says to plan for overflow, and direct it away from the house.
How we chose
We started from the question a gardener asks when a rain barrel is already on hand: how is it connected to the downspout? We opened three pages from a university extension, a state university water center and a municipal water district: the Penn State Extension Rain Barrel Construction Guide, the Colorado State water center Rain Barrel Installation Guide (PDF), and the Las Virgenes Municipal Water District installation guidelines. We opened each on 2026-10-22 and searched its text for placement, height, diverter, hose, overflow, maintenance and winter. We kept only statements a page makes in plain words. The table compares the three pages on the same items, and where two pages give different figures we show both.
What we could not verify
The three pages cover the install well, but they leave several points open. None of them gives a price for a barrel, a diverter kit or a hose, and none names a product, which keeps the guide to the method.
What the sources do not say
The sources do not agree on the spigot height, and the table shows both figures. They do not say how much rain a barrel of a given size can catch from a roof of a given size, and they do not give a rule for the overflow pipe’s diameter. They do not describe a full winter shutdown, and the Las Virgenes page is written for its own climate and its own earthquake straps, so its advice is a local example rather than a general rule. The Penn State page does not give an overflow plan, which is why the overflow section relies on the Colorado State and Las Virgenes pages.
Frequently asked questions
How close should the barrel be to the downspout?
Penn State says to keep the barrel within three feet of the downspout. The Las Virgenes page says to place the barrel near a gutter downspout, and it does not give a distance.
How high should the diverter sit on the barrel?
The diverter’s height should match the barrel’s fill hole, which both Penn State and Colorado State put at 3 inches from the top. Mark the downspout with a level from the barrel’s fill hole.
Does the downspout have to be cut?
The Las Virgenes page says the downspout will likely need to be shortened and may need elbows added. Penn State and Colorado State both fit the diverter into a hole cut in the downspout.
Where should the overflow go?
Colorado State says to direct overflow away from the house or flood-prone areas, and it says the overflow can go toward a lawn or garden. The Las Virgenes page says to divert it to the garden.
How is the setup checked after installation?
Run a hose of water through the gutters into the barrel, as the Las Virgenes page advises, and watch the diverter, the hose and the joints for leaks. Penn State also recommends that you inspect the barrel regularly for any leaks.
Bottom line
Set the barrel on a level, firm base close to the downspout, mark the diverter height from the barrel’s fill hole, fit the diverter with its cup facing up, and plan the overflow before you fill the barrel.
Once the barrel is connected and running, the next step is getting the water to the plants. See our guide to hose attachments for watering plants, and for the hose connection at the outlet, see connecting a hose to PVC pipe.
Sources
- https://extension.psu.edu/rain-barrel-construction-guide (opened 2026-10-22)
- https://watercenter.colostate.edu/wp-content/uploads/sites/20/2025/04/Colorado-Rain-Barrel-Installation-Guide.pdf (opened 2026-10-22)
- https://www.lvmwd.gov/rain-barrel-installation-guidelines (opened 2026-10-22)
