What Is a Rain Barrel?
Rain barrels are containers that capture the rain flowing off your roof through a downspout. This runoff is non-potable, meaning it is not safe to drink. It is safe to use for watering gardens, lawns, and trees, and also for washing cars or outdoor areas.
You can make your own rain barrels or buy them ready-made. Rain barrels, and the supplies to make them, are available at most garden, hardware, and home improvement stores. Premade residential rain barrels are commonly available in 55-gallon and 90-gallon sizes.
Commercial and industrial properties may find cisterns more suitable than rain barrels. Cisterns hold more water and are more durable. Their capacity makes them better suited for buildings with large roof areas. Permitting is required if you install a cistern underground.
How Rain Barrels Work
Rain barrels sit at the end of downspouts, usually next to buildings. By capturing and storing rainwater, rain barrels reduce the volume and flow of runoff into the sewer or stormwater systems.
Keep in mind that rain barrels are not a stand-alone stormwater management system. They typically fill up in the first rains of the season and will need to overflow to a safe disposal location throughout the rainy season. Garages and outbuildings that do not have basements are best for rain barrels. A patio cover or carport away from the building may also be suitable.
Remember, a rain barrel may overflow nearly every time it rains. When the barrels are full, an overflow pipe must allow the extra water to flow into a rain garden, lawn, or other landscaped area or into the sewer/stormwater system if there is no safe landscape alternative.
Rain Barrel Design Requirements
There are few requirements for rain barrel designs. Rain barrels can vary in size, shape, and material.
The fundamental elements are:
- A sealed lid with an opening for the downspout to drain into.
- An overflow pipe at the top. Do not install a hose bib/spigot on the overflow. The barrel must be allowed to drain when it becomes full.
- A hose bib/spigot for a hose or faucet installed at the bottom of the barrel.
- Screen the opening to control mosquitoes and other insects.
To stay safe and avoid damaging buildings or structures:
- Place rain barrels on flat, stable surfaces.
- In areas where it is safe to do so, you can direct overflow from the barrel to the yard or landscape area. The area must meet the safety requirements listed for Downspout Disconnection. If that is not possible, use your home’s existing disposal system (sewer/stormwater pipe, drywell, etc.) to safely direct excess rainwater away from your building.
- Only collect water from the roof for reuse. Do not collect water from parking or pedestrian areas.
- Rain barrels may have to be elevated in order to allow gravity to move the water into the landscape.
- Be careful irrigation hoses and overflows don’t create tripping hazards across walkways or in front of gates.
When to Call a Professional
Professionals are not required to build or install a residential rain barrel. If you have questions about using rain barrels on your property, contact Environmental Services Private Property Drainage Inquiries.
Rainwater harvesting, collecting and storing stormwater runoff for non-potable uses within a house or building or as part of an irrigation system, requires permits and the help of a professional.
Costs and Permits
A homemade rain barrel can be constructed for about $30. Ready-made rain barrels can range from $50 to $300, depending on size and material.
Rain barrels are not approved for projects that trigger the requirements of the Stormwater Management Manual. Permits are required for rainwater harvesting. See the Stormwater Management Manual.
Maintenance Requirements
Rain barrels require regular inspection and maintenance, especially during the rainy season, to make sure they are working properly and safely overflowing to a designated location. Be sure to:
- Inspect for leaks (especially at spigots and connection points).
- Inspect for and remove debris (weekly during the rainy season).
- Empty rain barrels after rain events in the wet season.
- Clean the interior annually with vinegar or another non-toxic cleaner.
- If the barrel is opaque, it is recommended to paint the barrel to inhibit algae/mold growth inside the rain barrel.
Portland’s Clean River Rewards Program
Residential and commercial property owners who install qualified stormwater management solutions may be eligible for discounts on the stormwater charges of their sewer, stormwater, and water bill through Clean River Rewards.
Rain barrels that meet the safety and space requirements outlined above and allow extra water to soak into the ground at a safe distance from buildings or foundations may be eligible for Clean River Rewards. Visit Clean River Rewards to learn more.
Find More Resources
How to Build Your Rain Barrel. This printable how-to guide from Environmental Services will walk you through the steps to add rain barrels to your property.
Portland’s Stormwater Management Manual. Although rain barrels are not an approved solution for projects that trigger the City’s Stormwater Management Manual, the manual provides complete details for building and maintaining many other stormwater solutions. See the Stormwater Management Manual to learn more.