Rain barrel systems capture and store rainwater from your roof for later use in the garden. This simple, sustainable practice reduces water bills, decreases stormwater runoff, and provides plants with naturally soft, chlorine-free water they love.
Benefits of Rain Barrels:
- Free water for gardens, lawns, and washing
- Reduces municipal water consumption by 40%+ for outdoor use
- Decreases stormwater runoff and erosion
- Provides chlorine-free water plants prefer
- Lowers water bills during peak summer months
- Reduces strain on municipal water systems
- Available during water restrictions in many areas
- Environmentally responsible water management
How Much Water Can You Collect?
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A surprising amount! One inch of rain on 1,000 square feet of roof yields approximately 600 gallons of water. Even a modest 500 square foot roof section can fill a 50-gallon barrel multiple times during a single rainstorm.
Collection Calculation
Use this formula: Roof area (sq ft) × rainfall (inches) × 0.6 = gallons collected. For example: 1,000 sq ft × 1 inch × 0.6 = 600 gallons. The 0.6 factor accounts for evaporation and spillage.
Sizing Your System:
- Small garden (under 200 sq ft): 50-gallon barrel
- Medium garden (200-500 sq ft): 100-gallon or two 50-gallon barrels
- Large garden (500+ sq ft): 200+ gallons in connected barrels
- Consider your average rainfall and dry spell duration
- Factor in how quickly you'll use stored water
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Material Options
Plastic (polyethylene): Most common, lightweight, affordable, UV-resistant options available. Wood: Attractive whiskey barrel style, heavier, may need liner. Metal: Durable galvanized or decorative copper, can heat water in sun.
Essential Features:
- Screened inlet to filter debris and prevent mosquitoes
- Spigot near bottom for gravity-fed watering
- Overflow outlet to direct excess water away from foundation
- Opaque material to prevent algae growth
- Secure, child-safe lid
- Flat back design for placement against walls
- UV-resistant material for outdoor durability
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Step-by-Step Installation:
- Choose location near downspout, close to garden
- Create level, stable base using cinder blocks or stand
- Elevate barrel 12-24 inches for gravity pressure
- Cut downspout to barrel height plus 2 inches
- Install diverter kit or direct downspout into barrel
- Connect overflow outlet to outlet, direct away from foundation
- Attach hose to spigot for easy watering access
- Install first flush diverter to improve water quality (optional)
Location Considerations
Place barrels on the north or east side of buildings to minimize algae growth from sun exposure. Ensure the ground slopes away from your foundation. Keep barrels accessible for maintenance and close to where you'll use the water.
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Mosquito Prevention
Mosquitoes can breed in standing water within days. Keep screens intact, seal all openings, and use mosquito dunks (Bti) if needed. Empty barrels completely if not using water regularly.
Regular Maintenance Tasks:
- Clean inlet screen monthly during leaf season
- Flush sediment from bottom quarterly
- Check and clean overflow outlet before rainy season
- Inspect for cracks or leaks annually
- Drain and store or winterize before freezing weather
- Clean interior annually with diluted bleach solution
- Replace worn spigot washers as needed
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Water Quality Notes
Rain barrel water is excellent for ornamental plants, lawns, and established vegetables. Avoid using for drinking, cooking, or bathing without proper treatment.
Link barrels together to increase storage capacity. Connect overflow outlets in series, or link barrels at the bottom for equalized water levels. Use 1" or larger fittings to allow adequate flow between barrels.
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These quality rain barrels and accessories will help you start harvesting rainwater:
Recommended Products
Good Ideas Rain Wizard 50 Gallon Barrel
$119.99
PROS
- Attractive oak barrel design
- Flat back for wall placement
- Includes spigot and overflow
CONS
- Plastic construction
- Screen could be finer
RTS Home Accents 50-Gallon ECO Rain Barrel
$99.99
PROS
- Planter top for flowers
- Made from recycled materials
- Attractive terracotta look
CONS
- Spigot placement could be lower
- Overflow fitting basic
Oatey Mystic Rainwater Collection System
$29.99
PROS
- Easy diverter installation
- Automatic overflow return
- Works with any barrel
CONS
- Requires downspout cutting
- Hose not included
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Frequently Asked Questions
Is it legal to collect rainwater?
Rainwater harvesting is legal in most U.S. states, though some have regulations on collection amounts or methods. Check your local and state laws before installing. Many areas actually encourage rain barrels with rebate programs.
Can I use rain barrel water on vegetables?
Yes, rain barrel water is safe for vegetable gardens. Apply water to soil rather than leaves, and avoid watering edible parts close to harvest. The main concern is roof contaminants, which are minimal for most residential roofs.
How do I prevent my rain barrel from freezing?
In freezing climates, drain barrels completely before winter and disconnect downspout diverters. Store barrels in a garage or shed, or leave them outside empty with spigots open. Frozen water can crack even heavy-duty barrels.
Why is my rain barrel water pressure so low?
Rain barrels rely on gravity, providing only 0.4 PSI per foot of elevation. Raise your barrel higher (2-3 feet) for better pressure, or use a small pump. For drip irrigation, gravity pressure is usually sufficient.
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Written by
Sarah Williams
Sustainable living advocate and water conservation specialist with 12 years of experience in residential rainwater harvesting systems.