Need Free Water? Build a Rain Barrel




For the price of a 55 gallon plastic barrel (sometimes free), and about $10 in parts, you can build your own rainwater collection system. Water is good. Free water is better.

If you already know that water won't run uphill and how to handle a drill, you can do this. The most ingenious part of the design is the hose-to-barrel connection. Since the attached hose will frequently be tugged during normal use, it is important to use a mechanical connection rather than a glued connection.

This design uses a simple garden hose washer, standard garden hose parts, and a special adapter, that's not really all that special. It's expandable and useful for more than just capturing rain water.

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Step 1: Got Parts?

You will need a barrel. The bigger the better. 55 gallon is good. I like plastic, but metal will work. Don't use barrels that held something toxic in a former life, go for something wholesome, like lawn fertilizer, or laundry detergent. I picked up this one at a local recycler for $4.

Also, while in town, pick up a garden hose valve, garden hose washer, and a MHT to FPT 3/4" plastic adapter. What? MHT = Male Hose Thread. FPT = Female Pipe Thread. Plastic = plastic. You'll know it when you see it. Less than $10 total.

I had some old parts handy to draw from.

The gutter modification comes later.

Step 2: Tools Needed

A drill. 1" drill bit. A Keyhole saw. That's all you need to modify the barrel.

To modify a gutter downspout, you will also need a heavy duty pair of scissors (or sheet metal snips), about 10 small sheet metal screws, and a small drill bit to pre-drill for the screws. A pop-rivetor would also work. The special pliers shown in the photo are for "shrinking" sheet metal. Optional.

Step 3: Saw an Opening in the Top of the Barrel

Just like in the photo. Unless you want to put the opening off-center. That may work better.

Step 4: Attach Garden Hose Valve

Drill a 1" hole near the bottom of the barrel. The adapter and washer go on the inside of the barrel. The valve goes on the outside. The toughest part of this is that it requires someone with a really long arm to hold the adapter while someone else screws on the hose valve.

Step 5: Modify the Downspout

Downspouts are easy to modify. Look at one closely, it will be apparent how they fit together. Use the small drill bit to drill out existing rivets if necessary. Some are put together with sheet metal screws. Just be flexible with your tools and mind, and you will be able to build a downspout to direct rainwater into your barrel.

The parts photo shows a flexible plastic downspout that may also work.

Step 6: Add More Barrels

I added a secondary barrel using a garden hose Y adapter as shown in the photo. I modified it later to replace the Y adapter with an additional dedicated hose to fill the secondary barrel. Putting your hose connections near the bottom of the barrel allows most of the water to be utilized from all barrels, even the secondary ones.

I learned that one 55 gallon barrel can fill up in about 10 minutes of heavy rain. The secondary barrel would only partially fill in that time due to the relatively small diameter of the garden hose. Adding two or three or more secondary barrels, each with its own dedicated fill hose from the main barrel, will work much better, saving more water during those times of heavy downpour.

Make your hose-barrel connections the same way for secondary barrels. The second photo shows a cut-away mock-up of the hose-barrel connection. In this case, a quick-release brass connector just happened to work for the inside job. However, the MHT to FPT adapter is better since it has a larger diameter. A different garden hose valve did duty for the outside job.

Step 7: Enjoy Free Water!

Here's a photo of the rain barrel receiving its first deluge of rain water. There's a piece of window screen on the top of the barrel to filter out debris. The screen is also important in preventing mosquitos from entering and mulitplying.

As a bonus, this system makes a splendid watering system for gardens during dry seasons. I use tap water to fill the barrel with 15 or 20 gallons, and then use the barrel outlet hose to meter out water to specific garden areas. You can walk away from it, and your garden will slowly receive that 15 or 20 gallons, no more, no less. Very nice for those times when rain water is in short supply.

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    98 Discussions


    4 years ago on Step 4

    To increase the flow of water out of the barrel use a 3/4" 1/4 turn ball valve instead of that hose valve. The ball valve has a much bigger diameter hole inside to allow water out that the hose valve.

    2 replies

    Reply 4 years ago on Introduction

    That is a ¼ turn ball valve although the inside opening doesn't look like ¾".


    Reply 4 years ago on Introduction

    1/4 turn ball valves come in several sizes, so that hole inside of that one is the same as a garden faucet. A 3/4" 1/4 turn ball valve will have a much larger hole inside, and still fit a garden hose. Check out the video on youtube called "Rain barrel water pressure/volume demonstration" to see the difference.


    4 years ago on Step 6

    Did you use a 25ft hose to connect the two barrels? I'm trying to keep costs as low as possible.


    You're not doing this for drinking water. From the comments, there are a lot of daft people looking at this instructable.

    This is water that you will use for watering your garden/lawn.

    Clearly common sense is no longer common.


    5 years ago on Introduction

    I'd suggest a large overflow port for places where heavy rains are common.

    OR just use an inexpensive DIY kit like this one

    Filtering on the downspout keeps the debris from matting down on the top screen material:


    8 years ago on Step 7

    Do you know how much money it will save on your water bill? That is amazing! Thank you for sharing.

    1 reply

    Reply 7 years ago on Introduction

    you should realy filter the water and boil it before ingesting as it can pick up tar bird manure, and solvents off f a roof not to mention the noxious chemicals that are in our atmosphere, that this water was recently in contact with.


    8 years ago on Introduction

    We simply placed some feeder goldfish in our rain barrell to eat the mosquito larvae.


    9 years ago on Introduction

     has anyone looked into putting a deionizer into the spigot setup?  This would eliminate the risk of acid rain... and an activated charcoal filter should remove any other contaminants...

    1 reply

    Reply 8 years ago on Introduction

    The rain just ran over a roof.... I'd be more worried about what it picked up there (tar, solvents, bird poo, etc) than I would be about acid rain. This is meant for grey water type uses - drinking water is cheap enough (fractions of a cents a gallon) that I wouldn't recommend trying to pinch those pennies.


    Very nice rain barrel - simple and easy. I have built something similar, but tie the barrels together. I use a small pump from Home Depot to empty the barrels.

    You can see the beast here...

    Also includes step by step instructions with pictures.