How to Connect a Rain Barrel to a Downspout: Step-by-Step Install

Last updated: October 2026 · Written by the LawnVibe editorial team.

A rain barrel collects free water from your roof that you can use on gardens, pots and lawns. The key step is how you connect rain barrel to downspout so the barrel fills reliably and overflow goes somewhere safe. This guide covers choosing a spot, building a level base, the main connection methods, handling overflow and linking several barrels.

For an overview of rainwater systems, see our rainwater harvesting system for garden guide. To use the water for irrigation, see our rain barrel watering system guide.

How much water can you collect?

A common rule of thumb is that one inch of rain on 1,000 square feet of roof produces roughly 600 gallons. A single downspout often drains only part of the roof.

Even a small roof section can fill a 50 to 60 gallon barrel in one storm, so overflow planning matters.

Choose the right spot

• Under a downspout that drains a good-sized roof section.
• Close to where you water to keep hoses short.
• On firm, level ground, since a full 55 gallon barrel weighs over 400 pounds.
• Away from the foundation for overflow, or with a way to route overflow away.
• In shade if possible to reduce algae.

Build a level base

Raise the barrel 12 to 18 inches so you can fit a watering can under the spigot and gain a bit of gravity pressure. Use concrete blocks, pavers or a purpose-made stand on compacted gravel. Check that it is level and stable; a full barrel that tips can be dangerous.

Ways to connect a rain barrel to a downspout

Method 1: Install a diverter kit

1. Set the barrel on its base next to the downspout.
2. Mark the downspout at the height recommended by the kit, often level with or slightly above the top of the barrel.
3. Cut or drill the downspout as the kit directs.
4. Insert the diverter and secure it.
5. Drill a hole in the barrel for the inlet fitting if needed.
6. Connect the hose from the diverter to the barrel.
7. When the barrel fills, water backs up and continues down the spout.

Method 2: Cut the downspout and add an elbow

1. Measure the downspout a few inches above the top of the barrel.
2. Cut it with a hacksaw and remove the lower section.
3. Attach a flexible downspout elbow.
4. Direct the elbow into the barrel's screened inlet.
5. Attach an overflow hose and route it away from the house.
6. Keep the cut section to reattach in winter.

Handle overflow

Overflow is essential. Route an overflow hose to a garden bed, rain garden or a downspout extension at least several feet from the foundation, or link to a second barrel. Diverter kits handle overflow automatically.

Link two or more barrels

Connect barrels with a short hose between their lower ports or overflow ports. Place them at the same height. When the first fills, water flows into the next.

Choosing a rain barrel

Before you connect anything, make sure the barrel suits the job. Most home rain barrels hold 40 to 80 gallons. Look for an opaque, UV-resistant barrel, since clear or light-colored plastic lets in light that feeds algae. A good barrel has a screened inlet or lid, a spigot near the bottom, an overflow port near the top and a removable lid or large opening for cleaning. If you repurpose a food-grade drum, make sure it never held chemicals and rinse it thoroughly. Larger tanks of 100 gallons or more store more water but need a stronger base and more planning for overflow.

Tools and materials

• Rain barrel with spigot and overflow port
• Concrete blocks, pavers or a barrel stand
• Gravel for leveling
• Spirit level
• Diverter kit, or flexible downspout elbow
• Hacksaw or drill with hole saw, depending on method
• Tape measure and marker
• Overflow hose or downspout extension
• Fine mesh screen
• Thread seal tape for fittings

Preparing the downspout

Clean the gutters and downspout before installing so the first storm does not wash leaves and grit straight into the barrel. Check that the downspout is secure to the wall with straps above and below where you plan to cut. If the downspout is a different size or shape from what your diverter kit expects, such as round versus rectangular, look for an adapter or a kit made for that profile. Measure twice before cutting, since a cut too low means the barrel cannot sit under it, and a cut too high leaves water splashing.

Installing the spigot and overflow

Many barrels come with fittings already installed. If yours does not, drill a hole near the bottom for the spigot, a few inches up so sediment settles below it, and another near the top for the overflow. Thread the fittings in with thread seal tape and use rubber washers on both sides of the wall to prevent leaks. Fill the barrel partway with a hose and check for drips before the first storm.

Making the water easier to use

A spigot alone gives very low pressure. To fill watering cans easily, raise the barrel higher. To water beds directly, connect a soaker hose or low-pressure drip kit to the spigot, keeping runs short. For more pressure, a small submersible or inline pump can push water through a hose or sprinkler. Our rain barrel watering system guide covers these setups.

Winter care

Where temperatures drop below freezing, drain the barrel before the first hard freeze, leave the spigot open and disconnect it from the downspout. Reattach the downspout section or close the diverter so water flows down normally. Store the barrel upside down or indoors so it cannot fill and crack. Ice can split plastic barrels and damage fittings.

Maintenance after installing

Check the screen after storms and clear leaves, clean gutters at least twice a year and look for leaks around fittings. Once or twice a year, empty and clean the barrel to remove sediment and algae. See our guide on how to clean a rain barrel for steps. If the spigot slows or stops, see rain barrel not draining.

Diverter kits in more detail

A diverter is the cleanest way to connect a rain barrel because the downspout stays in one piece and the barrel cannot overflow onto the foundation. Most diverters work in a similar way: an insert fits inside the downspout and catches water flowing down the inner wall, sending it through a short hose to the barrel. When the barrel is full, water backs up the hose to the level of the diverter and the rest continues down the spout as usual. That is why the diverter must sit at or slightly above the top of the barrel.

Some diverters include a leaf filter or a winter setting that sends all water down the spout. Others are made for greenhouses, sheds and garages with smaller downspouts. Compare options in our review of the top gutter diverter kits for rainwater harvesting.

How many barrels do you need?

Start by comparing how much water your roof sends to a downspout with how much you use. A typical 55 gallon barrel can fill in a single moderate storm from a modest roof section, so many gardeners find one barrel overflows often. If you water a vegetable garden or several beds, two or three linked barrels, or a larger tank, may suit you better. In regions with long dry summers, storage runs out quickly anyway, so think of barrels as a supplement that covers a week or two of watering rather than a full replacement for tap water.

You can also place barrels at more than one downspout. A barrel near the vegetable garden and another near the patio pots cuts down on carrying water around the yard.

Where to put the overflow water

Overflow is a resource, not just a problem. Instead of sending it to the street, route the overflow hose to a nearby planting bed, a gravel-filled dry well or a shallow rain garden planted with species that tolerate both wet and dry spells. Keep the outlet at least several feet from the foundation and make sure the ground slopes away from the house so water does not flow back toward it. On a small lot, a simple downspout extension or splash block may be enough.

Testing the installation

After setup, run a garden hose into the gutter or wait for the first rain and watch the system work. Water should flow into the barrel without splashing, the overflow or diverter should take excess away from the house, and the spigot and fittings should stay dry. Check that the base has not settled once the barrel is full, and adjust if it leans.

Common installation mistakes

• Uneven or soft base, which lets a full barrel lean or tip.
• No overflow plan, sending water against the foundation.
• Diverter set too low, so the barrel overflows instead of backing up.
• Open, unscreened inlets that breed mosquitoes.
• Spigot set too low to fit a watering can.
• Forgetting to winterize in cold climates.

Rules and safety

Rain barrels are allowed in most places, and many cities and water utilities offer rebates or discounted barrels. A few areas regulate rainwater collection, so check with your local or state water authority before installing. Keep lids locked or screwed down so children and pets cannot fall in, and use collected roof water for plants rather than drinking.

Screen and secure the barrel

Use a fine mesh screen over openings to keep out mosquitoes, leaves and debris, and keep lids secured for child and pet safety.

The EPA promotes rain barrels as one way to reduce stormwater runoff.

The bottom line

To connect rain barrel to downspout, place the barrel on a raised, level base near the downspout, then fit a diverter kit or cut the downspout and add a flexible elbow. Always plan for overflow, screen openings against mosquitoes and debris and link more barrels if one fills too fast.

Frequently Asked Questions