Rain Barrel Basics: Collecting Rainwater for Your Home Garden

Louisville, Tennessee gets about fifty inches of rain every year. That is enough water to fill more than twenty thousand five-gallon buckets. Most of it hits your roof and runs into the street. A rain barrel catches a small piece of that and puts it to work in your garden instead.

It is one of the simplest forms of home water collection, and it is also one of the most affordable. You can set up a basic system for under fifty dollars if you already have some of the pieces around the house. Even a complete new setup usually stays under a hundred fifty dollars.

This guide walks you through what a rain barrel system is, what you need to build one, how to connect it to your gutters, and how to use the water safely in your vegetable garden. No plumbing experience required.

Why Bother With a Rain Barrel

Rain barrels serve a few purposes beyond saving money on your water bill.

Your plants prefer it. Rainwater is naturally soft and free of chlorine. Most municipal water carries chlorine or chloramines that can build up in soil over time. Rainwater does not.

It is free water. Once the barrel is set up, every rainstorm is a free refill. In Tennessee, that means dozens of refills per year from a single barrel.

It reduces runoff. A full barrel diverts hundreds of gallons of water that would otherwise rush into storm drains, carrying soil, fertilizer, and debris into nearby streams.

It builds a useful habit. Setting up a rain barrel gets you thinking about how water moves through your property. That mindset is useful whether you are planning a garden, managing a homestead, or just trying to live more lightly on the land.

Tennessee makes it easy. The state has no restrictions on residential rainwater harvesting. You do not need a permit, you do not need to report how much you collect, and you do not owe anyone for the water that falls on your roof.

What You Need to Build a Simple Rain Barrel

You do not need to buy a finished kit. A basic rain barrel system has five components:

The barrel. A 55-gallon food-grade drum works well. These are widely available from local businesses, farm supply stores, or online marketplaces. If you get one secondhand, make sure it held food-grade material and not chemicals. A food-grade drum has already held things like pickles, mustard, or fruit syrup. It is safe for garden use. A drum that held industrial solvents or unknown chemicals should be discarded.

A stand. The barrel needs to sit higher than the ground so water pressure at the spigot works properly. A simple stand made from cinder blocks or a wooden pallet works fine. Make sure the surface is level. A barrel filled with water weighs around 460 pounds.

A diverter. This is the piece that connects the barrel to your gutter downspout. An Oatey downspout diverter costs about fifteen to thirty dollars and fits most standard downspouts. It lets you divert water into the barrel during rain and let it pass through normally when the barrel is full.

A screen or mesh. Cover the top of the barrel with fine mesh to keep out leaves, mosquito larvae, and other debris. A simple piece of hardware cloth or window screen held in place with a rubber band or zip ties works well.

An overflow hose. When the barrel is full, excess water needs somewhere to go. A short piece of flexible hose attached to the overflow port or the top lid keeps water from pooling at the base of the barrel and eroding your yard.

Optional but useful additions:

• A spigot or faucet near the bottom for easy access. Many barrels come with a pre-drilled hole for this. A basic brass spigot costs about five dollars.
• A lid or tight cover to prevent debris and mosquitoes from entering.
• A chain to keep the spigot from being lost or damaged.

How to Set It Up

Here is the straightforward process:

1. Choose a location. Place the barrel near a downspout that drains from a clean roof surface. Asphalt shingles and metal roofs are both fine. Avoid barrels positioned under trees that drop a lot of leaves or pine needles, since those clog diveters quickly. Keep the barrel on a stable, level surface.

2. Build or position the stand. If you are using cinder blocks, stack two or three to get the barrel about two to three feet off the ground. If you are using a wooden pallet, make sure it is sturdy and sits on a level patch of ground. Place the barrel on top and check that it sits level.

3. Install the diverter. This is the main connection point between your gutter and the barrel. Cut the existing downspout with a hacksaw, insert the diverter, and reattach the downspout below it. The diverter will automatically send water into the barrel when it is dry, and let water flow through the downspout when the barrel fills up. Follow the instructions on the diverter package. They are usually simple.

4. Drill a hole for the spigot. If your barrel does not already have one, measure a few inches up from the bottom and drill a one-inch hole. Screw in the brass spigot and tighten it with a wrench. Add some plumber's tape around the threads for a tighter seal.

5. Install the overflow hose. Attach a short hose to the overflow port near the top of the barrel. Direct the other end away from your foundation so excess rain does not pool against the house.

6. Add the screen. Cut a piece of fine mesh to fit over the top opening. Hold it in place with a zip tie, rubber band, or a lid with small holes. The goal is to keep debris out while letting rain in.

7. Test it. Wait for the next rain or pour a bucket of water into the downspout and check for leaks. Make sure the diverter switches between the barrel and the downspout smoothly.

Using the Water in Your Garden

Rain barrel water is great for most garden use, but there are a few things to keep in mind:

Water at the base of plants. Direct the water onto the soil, not the leaves. This is especially important for edible crops. Wet leaves can spread disease, and rain barrel water has not been treated for pathogens the way municipal water has.

Avoid overhead watering on leafy greens. If you are growing lettuce, spinach, or similar crops, do not spray the water over the leaves. Stick to the base of the plants or use it on non-edible crops like flowers and ornamentals.

Wash produce before eating. This is good practice regardless of where your garden water comes from. Washing vegetables with clean tap water removes any surface contaminants.

Don't worry about the "not potable" label. Rain barrel water is not safe to drink. But for watering plants, that is exactly what it is for, and no one expects you to drink your garden water.

Good uses for rain barrel water:

• Tomato, pepper, and eggplant plants
• Herbs and flowers
• Fruit trees and berry bushes
• Lawn irrigation
• Washing garden tools and pots

Not ideal for:

• Leafy greens where water contacts the edible part
• Seed starting trays (the water may carry debris)

Keeping Your Barrel Working

A rain barrel is low maintenance, but it does need a few simple checks:

Every rainstorm: Clear leaves and debris from the screen on top. A clogged screen slows down water intake and can cause overflow.

Once a month: Check for mosquito larvae. If you see tiny wriggling things in the water, drain the barrel and clean it. The mesh screen should catch most mosquito eggs, but over time it can degrade and let tiny larvae through.

After heavy use: If you use a lot of water during a dry spell, the barrel may run low. Plan ahead. If you know rain is coming, you can drain the barrel in advance so it is ready to collect again.

Check the spigot: A dripping spigot wastes water and can create a mosquito breeding spot near the ground. Tighten it or replace the washer if it leaks.

Winter Care

A rain barrel full of water will crack if that water freezes. In Zone 7a, you will want to drain the barrel before the first hard frost of winter.

Drain the barrel completely. Turn off the spigot, remove the diverter if possible, and let any remaining water drain out. Wipe the inside if you can reach it.

Disconnect the diverter. Store it indoors or at least in a place where it will not freeze. If your diverter design allows it, you can leave it in place during winter and simply divert the downspout away from the barrel entirely.

Leave the lid off or loosely cover it. You do not want a hollow barrel filling up with rain during winter and then freezing solid. A loose cloth cover keeps debris out while letting rain escape.

Store the barrel if you can. Flipping it on its side or moving it to a garage or shed prevents damage from ice or wind. If it is too heavy to move, draining it and leaving it upright is also fine.

Getting Started

You do not need to get everything perfect on the first try. A plastic trash can with a spigot and a screen works fine to start. You can upgrade to a proper barrel and diverter later when you know it is something you want to keep.

The point is to start collecting and using rainwater. Once you see how much water a single barrel captures during a thunderstorm, you will probably want a second one. And a third. But that is a project for another day.

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— C. Steward 🌾