How to Use a Rain Barrel: From Installation to Maintenance 

Rain barrel connected to a house using a downspout

Want to harvest rainwater but don’t know where to start? You’ve come to the right place. This practical guide on how to use a rain barrel will walk you through the steps of building your own rain barrel and connecting it to your downspout. We also include tips on how to maintain your rain barrel and how to use the water you collect.

3 steps to build your own rain barrel 

You can save a significant amount of money by building your own rain barrel as opposed to buying one from the store. The DIY route is especially frugal if you already have a large outdoor trash can with a lid, a plastic barrel, or any other sealed plastic container you could repurpose to hold water. 

This section only tells you how to put a DIY rain barrel together. If you purchased a ready-made rain barrel and just need to know how to install it, skip to the next section, “4 steps to install a rain barrel.” 

Note: Before you start building, learn about the different parts of a rain barrel and their purposes in “What Is a Rain Barrel?”

What you’ll need

  • Large outdoor trash can with lid, plastic drum, or another large container made of food-grade plastic
  • Electric drill with a 1-inch drill bit 
  • ¾-inch spigot 
  • Metal and rubber washers 
  • Silicone sealant 
  • 10-foot PVC pipe, garden hose, or sump pump drain hose 
  • Landscape fabric or window mesh screen 
  • Fine-toothed saw 
How a Rain Barrel Works - Downspout, through screen (remove debris), into barrel | Overflow valve close to top | Spigot close to bottom | Barrel on a stand

Step 1: Install the spigot 

Start by turning your large plastic trash can or container on its side. The side facing up should be the same side that will face away from your home. 

About 5 inches above the bottom of the barrel, drill a 1-inch hole in the side facing up. Insert a ¾-inch spigot into the hole with one metal washer and one rubber washer each on the inside and outside of the barrel. Apply silicone sealant on both sides to make the outlet waterproof.

Design tip: Make sure the spigot is high enough that you can fit a watering can or bucket under it. 

Step 2: Add an overflow valve

On the same side as the spigot, drill another hole 2-3 inches from the top of the barrel. The hole should be just large enough to fit your overflow pipe or hose. Water will drain out of this hole when the barrel is almost full to keep it from overflowing. 

Insert a PVC pipe, garden hose, or sump pump drain hose into the overflow hole so you can direct where the excess water goes. The pipe or hose should be able to carry excess water at least 10 feet away from your home’s foundation. Seal the inside and outside of the hole with silicone sealant to prevent leaks and keep mosquitoes and other bugs from getting inside. 

Step 3: Prepare the lid

Cut a hole in the container’s lid with a fine-toothed saw (or any other tool that can cut thick plastic). The hole should be just large enough for your downspout or rain diverter to fit inside. 

Right underneath the lid, attach a sheet of permeable landscape fabric or a panel of window mesh to act as a debris screen. The screen will keep mosquitoes from laying eggs in your rain barrel and filter out leaves, twigs, and other debris. 

4 steps to install a rain barrel

Now that your rain barrel is ready to go — whether you made it yourself or bought it from your local garden center or hardware store — it’s time to install it underneath your downspout so it can collect rainwater. 

Before you install a rain barrel, though, check your state’s rainwater harvesting regulations. While it’s legal in some form in all 50 states, some states limit how much water you can collect and what you can use it for. Some local governing bodies (cities, towns, homeowners associations, etc.) ban rainwater harvesting altogether, so check local laws, too.

What you’ll need

  • Hacksaw
  • Rain diverter or downspout flex-elbow 
  • 2-4 cinder blocks, store-bought rain barrel platform, or 2-3 inches of gravel or sand 

Step 1: Choose the perfect spot for your rain barrel 

Your rain barrel should go right beneath one of your gutter system’s downspouts. Another requirement is flat, even ground so the barrel won’t tip over. 

If you plan to irrigate your lawn or garden with the water from your rain barrel, choose the downspout closest to the area that needs water. Because rain barrels don’t have much water pressure, the water from them may not be able to travel very far.

Step 2: Lay the foundation 

Once you’ve figured out where to put your rain barrel, you have two options for preparing the site:

  • Elevated platform: Elevating your rain barrel a few inches off the ground will increase the natural water pressure and flow rate. The platform you use to elevate it should be strong enough to hold the weight of the barrel when it’s full of water, which will probably be somewhere around 300 pounds. You can purchase a plastic rain barrel stand or use 2-4 concrete cinder blocks (depending on the size of the barrel).
  • Gravel or sand pit: In lieu of a platform, dig a pit 2-3 inches deep. Fill the pit with gravel or sand and smooth the top to create a flat surface on which to place the barrel. 

Design tip: If you want to use your rain barrel to power a soaker hose or drip irrigation system, it’s best to install it on a platform for the increased flow rate. 

Step 3: Face the spigot and overflow valve away from the house

Place your rain barrel on top of the foundation you just installed. The spigot and overflow valve should face away from the house so that 1) you have easy access to the spigot, and 2) the overflow valve carries excess water away from your home’s foundation. 

The overflow pipe or hose should deposit excess water in an appropriate drainage spot: at least 10 feet from the house, away from your lawn, and preferably into a rain garden or storm drain, if possible. 

Design tip: Connect the overflow pipe or hose to a second rain barrel to harvest even more rainwater (if your state laws allow). 

Step 4: Connect the downspout 

You’ll most likely have to adjust your downspout in some way to connect it to your rain barrel. Here are your main options:

  • Cut the downspout: With a hacksaw, cut your downspout so your rain barrel can fit underneath it. Once you’ve adjusted the length, either fit the end of the downspout directly into the hole in the lid of your rain barrel or connect a downspout flex-elbow from the end of the downspout to the hole in the lid. 
  • Install a rain diverter: To install a rain diverter, you’ll cut a small hole in the gutter above your rain barrel, then connect the diverter from that hole to the hole in the lid of the barrel. The best thing about a diverter is that you can open and close it at will. So, if your barrel is full or you don’t want to collect rainwater for any reason, you can close the diverter, and the water will flow through your downspout as usual. 

Safety tip: Before you cut your downspout, make sure there aren’t any wires running along the outside or inside. 

How to maintain a rain barrel 

After installation, rain barrels are pretty low-maintenance. However, here are a few things you can do to prevent damage and keep your rain barrel clean and pest-free. 

When to use the water 

Try to use the water in your rain barrel no more than one week after rainfall. Wait any longer, and the water will become stagnant, potentially harboring bacteria and attracting mosquitoes.

Even if you don’t plan to use the water, it’s a good idea to empty the barrel if water has been sitting in it for more than a week. 

When and how to clean your rain barrel 

At least once a year, disconnect your rain barrel from its downspout and scrub it thoroughly with antibacterial dish soap and water. Scrub the inside, outside, and all the water outlets. 

When you’re done, rinse out all the soapy water and leave your rain barrel to dry in the sun. Before reconnecting it, check that the seals around the water outlets are still watertight. If not, add a fresh layer of silicone sealant. 

What to do with your rain barrel in winter 

Before temperatures drop below freezing, disconnect your rain barrel from the downspout, empty it, and store it in the garage or shed until spring. If you live in an area that doesn’t freeze in winter, you can leave your barrel hooked up and continue harvesting rainwater year-round. 

How to use (and not use) rain barrel water 

One of the biggest benefits of installing a rain barrel is that you get free water for use around the house. But you can’t use that water for everything. As rainwater travels through your roof and gutters, it gathers dirt, bacteria, animal waste, and other pollutants that make it unsafe for consumption. 

Here are a few ideas for how you CAN use collected water from a rain barrel:

  • Irrigate your lawn (the most expensive lawn chore in terms of water use) 
  • Water your garden and houseplants 
  • Wash your driveway, patio, deck, or other outdoor areas 
  • Wash your car
  • Mop your floors 
  • Refill your toilet 

And here’s what you CAN NOT use untreated rain barrel water for: 

  • Drinking 
  • Cooking 
  • Bathing 
  • Cleaning surfaces that come in contact with food 

Gray area: There’s a bit of debate on whether or not it’s OK to use rain barrel water to irrigate vegetable gardens, fruit trees, herbs, and other edible plants. But you should be perfectly safe as long as you’re careful not to splash any of the water on the edible parts of the plants.

FAQ about rain barrels

1. What size rain barrel do I need?

That depends on how much water you expect to collect per week. You can estimate the amount of water using the average rainfall in your area and the size and shape of your roof. 

A general rule of thumb estimates that for every inch of rain, your rain barrel will collect about half a gallon of water per square foot of roof. Of course, your whole roof probably doesn’t drain into a single downspout, so, for this estimate, you’ll need to approximate how many square feet of your roof drains into one downspout. 

Formula: Inches of rain x 0.5 gallons of water x square feet of roof that drains into downspout = amount of water collected 

For example, if your area gets an average of 3 inches of rain per week in summer, and your roof is designed so that 50 square feet drains into one downspout, your calculation would look like this:

3 inches x 0.5 gallons x 50 square feet = 75 gallons of water 

So, if you wanted to collect as much rainwater as possible, you would need a 75-gallon barrel or multiple barrels that add up to 75 gallons.  

2. Can you use a rain barrel without gutters?

Yes. If you don’t have a downspout to drain directly into your rain barrel, place buckets around your home before the next rain to see where your roof drains the most. Whichever bucket is fullest after rain is where you should install your rain barrel. 

The process of building and installing a rain barrel is the same without gutters (except, of course, you won’t connect a downspout).  

3. How do you treat rain barrel water for drinking?

The CDC’s recommendations for making tap water safe to drink in emergencies also can be used to treat water from a rain barrel.  

Methods of treating water to make it potable (safe for drinking) include:

Boiling: Bring water to a boil for 1-3 minutes to kill viruses, bacteria, and parasites. Let the water cool for a few hours before drinking. 
Add disinfectants: Add a small amount of unscented household liquid chlorine bleach or chlorine dioxide tablets to decontaminate the water. See the CDC’s website for specific instructions. 
Use a water filter: If your household water filter is labeled as certified for NSF/ANSI Standard 53 or Standard 58, that means it can remove disease-causing parasites from water. However, filters don’t get rid of bacteria or viruses.

Reduce your landscape’s carbon footprint

Lawn and landscape care have more of an impact on the environment than you might think. They use thousands of gallons of water, many of the tools run on gas, and most fertilizers and pesticides contain harmful chemicals. 

Installing a rain barrel will help with water conservation. But what else can you do to reduce your carbon footprint without sacrificing the quality of your landscape? Here are some eco-friendly lawn care tips

  • Switch to phosphate-free, organic fertilizer
  • Practice integrated pest management (IPM) to reduce pesticide use
  • Water your lawn the right amount — don’t over- or underwater 
  • Mulch grass clippings when you mow the lawn
  • Replace part of your lawn with a less thirsty ground cover 

Your rain barrel has you covered for watering the lawn, but what about mowing, fertilizing, weeding, and other pesky chores? Lawn Love’s local lawn care pros can take those off your hands, too. 

Main Photo Credit: Ian Mackenzie | Flickr | CC BY 2.0

Jordan Ardoin

Jordan Ardoin is a writer and editor with a passion for sustainable, earth-friendly gardening and lawn care practices. When she isn't sharing her knowledge about lawn care and landscaping, you can find her curled up with a good book and a cat in her lap.