Rainwater Harvesting: Nature's Free Irrigation
Every time it rains, thousands of gallons of pure, soft, unchlorinated water flow off your roof and down the drain. Capturing even a fraction of this in rain barrels provides free irrigation that your plants actually prefer to treated tap water.
Collection Capacity
The numbers are impressive: one inch of rain on a 1,000 square foot roof yields about 600 gallons of water. Even a modest rainfall event fills multiple barrels. A single 55-gallon rain barrel is a start, but serious gardeners connect several in series for 200-500 gallons of storage.
Basic Setup
- Rain barrel: Food-grade 55-gallon drums are ideal. Many municipalities sell them at subsidized prices.
- Diverter: A downspout diverter redirects water from your gutter into the barrel and sends overflow back to the downspout.
- Screen: A fine mesh screen keeps out mosquitoes, leaves, and debris.
- Spigot: Install near the bottom for gravity-fed filling of watering cans. For more pressure, elevate the barrel on cinder blocks.
- Overflow: Route overflow away from your foundation with a hose or into a second barrel.
Why Plants Prefer Rainwater
Rainwater is naturally soft, slightly acidic (pH 5.6), and free of chlorine, chloramine, and fluoride found in municipal water. Many plants, especially acid-loving ones like blueberries and azaleas, grow noticeably better with rainwater.
Legal Considerations
In most of the US and Europe, rainwater collection is legal and even encouraged. However, some arid western US states have regulations limiting collection. Check your local laws before investing in a large system.
Maintenance
Clean screens monthly during fall (leaves). Drain barrels before winter in freezing climates. Flush the first gallon after a long dry spell to clear accumulated dust. Check connections and seals annually.
Track your water savings and garden irrigation in Seedtojar.