Join landscape design pro and Done-In-A-Weekend Projects video host Doug Scott to learn how to build a simple rain barrel irrigation system for your containers or small garden beds. Rain barrels are an excellent supplement to traditional irrigation systems—and depending on your climate, they can provide enough water to sustain your plants while meaningfully reducing your water bills.
Why Use a Rain Barrel for Garden Irrigation?
Rainwater harvesting is one of the most cost-effective and eco-friendly ways to water your lawn and garden. The average home can shed 600 gallons of water in just one hour of moderate rainfall—and with a proper rain barrel setup, you can capture and reuse up to 80% of that runoff for irrigation.
Whether you’re watering raised beds, container gardens, or a small lawn, collected rainwater is free, naturally soft, and ideal for plants.
How to Collect Rainwater: Your Two Main Options
1. Rain Barrels
Using a rain barrel is the most popular and accessible rainwater collection method for homeowners. You can find them at local home improvement stores, order online, or build one yourself, as Doug demonstrates in the video.
Rain barrels come in a range of sizes, so choose one that matches the typical rainfall in your region:
- High-rainfall areas: opt for a larger barrel (55+ gallons)
- Drier climates: a smaller barrel may be sufficient between rain events
Key features to look for:
- A covered top to keep out mosquitoes, debris, animals, and children
- A spigot near the bottom for easy drainage into smaller containers or a garden hose
- An overflow port near the top to manage excess water
2. Underground Rainwater Collection Systems
For larger-scale needs, underground cistern systems direct rainwater into buried storage tanks. These systems include a filtration pump that delivers water on demand. They’re significantly more expensive than rain barrels and require professional installation, but they’re worth considering if you have a large property or high water demands.
Rain Barrel Irrigation Tips: Best Practices & Safety Tips
Following a few simple guidelines will keep your system safe, effective, and compliant with local ordinances:
- For irrigation use only. Collected rainwater should never be consumed unless it has been properly filtered and tested for potability.
- Position barrels beneath or adjacent to your chosen downspout (your primary rainwater source). Keep them away from septic systems, utility lines, and HVAC components.
- Always keep barrel openings covered. Uncovered openings invite debris, pests, and pose a safety risk to children and pets.
- Install an overflow port so excess water can exit the system safely once the barrel reaches capacity.
- Plan your overflow drainage. Layer pea gravel beneath the barrel to absorb overflow, or connect the overflow port to your existing underground drainage system to direct water away from your home’s foundation.
DIY Rain Barrel Materials List
Before you get started, gather these supplies:
- 55-gallon water barrel or large garbage can with lid
- Tape measure
- Spigot kit with bulkhead fitting
- Drill with appropriate circular saw attachment
- Mesh screen
- Extension cord
- Waterproof silicone sealant
- Downspout diverter kit/materials
How to Build a Rain Barrel: Step-by-Step Instructions
Step 1: Drill Your Holes
Using your drill and hole-saw attachment, drill a spigot hole approximately 4 inches up from the bottom of the barrel. Then drill a second overflow hole approximately 2 inches from the top.
Step 2: Install the Bulkhead Fitting and Spigot
Insert the bulkhead fitting into the lower hole, then thread in the spigot. Make sure the spigot is oriented at a practical angle for attaching a hose or filling containers.
Step 3: Seal Everything
Apply waterproof silicone sealant around both the spigot and bulkhead fitting. Allow it to cure fully — following the manufacturer’s recommended drying time — before exposing the barrel to water.
Step 4: Connect to Your Downspout
You have two options here:
- Option A (barrel with solid walls): Cut a hole in the back of the barrel to accept a diverter kit and its bulkhead fitting, which connects directly into your downspout.
- Option B (garbage can with lid): Trace the outline of your downspout onto the lid and cut along that line. Place the can directly beneath the downspout.
In either case, orient the overflow hole so that water drains away from your home’s foundation.
Ready to get started? Watch Doug’s full step-by-step build video above, and check your local home improvement store for rain barrel kits and downspout diverter hardware.
Frequently Asked Questions About Rain Barrel Irrigation
No, not without proper treatment. Rainwater collected from rooftops picks up contaminants from shingles, bird droppings, gutters, and atmospheric pollutants. Use collected water for irrigation only, unless it has been professionally filtered and tested for safe consumption.
Position your barrel directly beneath or next to the downspout you plan to use as your water source. Make sure it sits on a stable, level surface—a slightly elevated platform (like cinder blocks) can increase water pressure at the spigot. Avoid placing it near septic lines, utility boxes, or HVAC units.
The most effective prevention is a tightly fitted lid and a mesh screen over any openings, including the inlet where water flows in. Some homeowners also add a small amount of mosquito dunks to the barrel, which are safe for plants and harmless to pets.
