A rain barrel is a storage system that collects rainwater from your roof via a downspout, holding it for later use on lawns and gardens.
A rain barrel captures roof runoff that would otherwise become stormwater, turning it into a free water source for your dry spells. Most standard barrels hold between 40 and 100 gallons, with 55 gallons being the most common size.
How Rain Barrels Work
A rain barrel sits directly under a downspout, connected by a flexible extension that diverts water into the barrel instead of the ground. A mesh screen on top keeps out leaves, mosquitoes, and debris. A spigot near the bottom lets you fill a watering can or attach a soaker hose, and an overflow valve near the top sends excess water back outside when the barrel is full.
The water collected is non-potable — meant for landscape use only. It works well on lawns, flower beds, shrubs, and indoor houseplants. Using it on vegetable gardens carries a contamination risk from bird droppings and roof debris, so stick to ornamental plants and grass.
Choosing and Setting Up a Barrel
Most prefabricated rain barrels are made from food-grade plastic, often repurposed 55-gallon shipping drums. The barrel must be opaque — clear or translucent plastic lets sunlight through, which promotes algae growth inside the barrel.
For a DIY setup, the basic steps are straightforward. Start with a heavy-duty plastic drum and wash it thoroughly with a bleach solution. Cut an 8-inch opening in the lid and cover it with fiberglass window screen. Install a 3/4-inch hose spigot a few inches from the bottom, then drill a 1-inch overflow hole about 4 inches from the top. Place the barrel on level ground elevated at least 1 foot — cinder blocks or a purpose-built stand work well. The elevation gives you gravity pressure for filling cans or running a short hose. Connect a flexible downspout extension to direct roof water into the screened opening.
A typical 50-gallon barrel measures about 42.5 inches tall with a 22.5-inch top diameter. Before buying, measure your downspout location to confirm the barrel fits.
Common Mistakes to Avoid
The most frequent errors cost people water, create maintenance headaches, or both. Use this quick-reference table to keep your setup running right.
| Mistake | Why It Hurts | The Fix |
|---|---|---|
| Using a transparent barrel | Sunlight grows algae inside | Use opaque plastic or paint the barrel |
| Spigot installed too high | Leaves gallons of usable water trapped below the tap | Install spigot within 2–3 inches of the bottom |
| No overflow valve | Water backs up the downspout or pops the lid | Drill a 1-inch overflow hole 4 inches from the top |
| Insufficient elevation | Weak water pressure from gravity alone | Raise the barrel at least 1 foot off the ground |
| No screen on the opening | Mosquitoes breed and debris clogs the spigot | Cover with fiberglass window screen |
Another common oversight is leaving the barrel full during freezing weather. Expand ice can crack the container or damage the spigot. Drain and disconnect the barrel before the first hard freeze.
If you decide a rain barrel fits your setup, check out our tested picks for the best contemporary rain barrels to find a model that matches your yard and style. Contemporary designs hold the same water but look better doing it — some double as planter bases or decorative urns.
Rain barrels are a low-effort way to cut your outdoor water bill and give your plants a consistent water source through dry periods.
FAQs
Can I drink water from a rain barrel?
No. Rain barrel water is non-potable and intended for landscape use only. Roof runoff picks up bird droppings, dust, and chemical residue from shingles. Never use it for drinking, cooking, or bathing.
How often do I need to clean a rain barrel?
Inspect the screen and spigot every few months, and clean the interior once a year. Drain the barrel fully, scrub with a bleach solution (1 part bleach to 10 parts water), rinse, and let it dry before reconnecting.
Will a rain barrel attract mosquitoes?
Only if the opening is uncovered. A tight-fitting mesh screen blocks mosquitoes from entering and laying eggs. Keep the screen intact and debris-free, and you will not have a mosquito problem.
References & Sources
- EPA. “Soak Up the Rain: Rain Barrels.” Overview of rain barrel benefits and installation basics.
- Mass.gov. “Rain Barrels and Other Water Conservation Tools.” Guide to using rain barrels for residential water conservation.
- Penn State Extension. “Why Use a Rain Barrel?” Research-based explanation of rain barrel benefits and proper use.