Rain barrels capture and store rooftop runoff from gutter downspouts for later use in landscape irrigation. They represent the most accessible and affordable entry point for residential stormwater management, reducing the volume of runoff that leaves a property during rain events.

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The Problem:
A typical residential roof can generate hundreds of gallons of stormwater during a single rain event. When that water flows unchecked from downspouts onto the landscape, it can erode soil, flood planting beds, and contribute pollutant-laden runoff to local waterways. Most homeowners have no system in place to capture this water before it becomes a problem.
The Solution:
Rain barrels intercept downspout flow and store it for later use. Even a single 40-gallon barrel can capture a meaningful portion of runoff from a small roof area. The stored water can then be used for garden irrigation, reducing both stormwater volume and municipal water consumption.
Stormwater Control vs. Irrigation Storage
Rain barrels can serve two distinct purposes. For irrigation storage, the barrel fills during rain events and the homeowner draws water down manually for garden use. For passive stormwater control (drawdown), a valve is left partially open so the barrel slowly empties between storms, ensuring capacity is available for the next rain event. The demonstration site illustrates both approaches.
Key Components
• Inlet screen at the top to keep bugs, leaves, and debris out of the water supply • Overflow mechanism that directs excess water away from the home and toward landscaping • Spigot positioned at least 3 inches above the bottom of the barrel for filling watering cans or attaching a hose • Stable, flat surface at least 3 inches off the ground to allow gravity-fed water flow

See the in Action

At the demonstration site, two 40-gallon rain barrels are positioned on concrete block bases (approximately 3 inches above ground level) to receive runoff from the green roof display table. A divided gutter on the table directs water through downspouts to each barrel, with each barrel catching half of the roof water from one side.

Practice Type: Rainfall harvesting and storage (small volume)

Scale: Two 40-gallon barrels connected to the green roof display table

Cost Range: $50–$200 per barrel (installed)

Best For: Any home with gutters and downspouts

Dual Purpose: Stormwater control and supplemental irrigation supply

Maintenance

Task
Frequency
Details

Screen cleaning

Monthly during leaf-fall season

Remove leaves and debris from inlet screens to maintain flow

Mosquito prevention

Ongoing

Ensure all openings are tightly screened; check for gaps after storms

Seasonal drainage

Before first freeze

Drain barrels completely and disconnect downspouts if freezing temperatures are expected

Interior cleaning

Annually (spring)

Flush barrel with clean water to remove sediment buildup; inspect for algae

Spigot and overflow check

Seasonally

Test spigot for leaks; verify overflow directs water away from foundation