Introduction: How to Build a Rain Water Collector

Picture of How to Build a Rain Water Collector

In this instructable, I will show how I made a rainwater collection system to water my garden. This helps to conserve water and make good use of a free and renewable resource.

Note that this involves using many different tools and proper safety precautions should always be taken.

Step 1: The Beginning - Installing the Posts

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To begin, I laid out a 55 gallon drum on the ground and dug a hole on either side in the spot that the poles (4x4 pressure treated lumber posts) were going to go.

Step 2: Installing the Posts Continued

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With the first post in the ground, I leveled it off with a level and propped it into place with scrap wood. Then, I began to mix the concrete. This entire project took three 50lb. bags of fast-drying concrete. With the concrete mixed to the right consistency, I poured it around the base of the post.

Step 3: Installing the Posts Continued

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The second post went in the same way as the first. From end to end -including the posts, it wound up measuring 39 inches.

Step 4: Installing the Posts Continued

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With the front two posts in place, I took a barrel and laid it back into place. This made it possible to judge where the last two posts should go.

Step 5: Installing the Posts Continued

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Of course, each post got 6 screws in the base to help them stay in the concrete.

All screws used in this project were 2 1/2 inch coarse-thread exterior screws.

Step 6: Installing the Posts Continued

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With the last two posts in, the concrete is allowed to dry and harden.

Including the posts, the front and back both measured 39 inches and the left and right sides both measured 38 inches. However, anybody attempting this should measure and place the posts in whatever configuration that is best.

Step 7: Building the Barrel Braces

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While the concrete dried, I began to make the barrel braces. These need to be strong, since they will be supporting the entire weight of the barrels.

For this, I used two pieces of 2x4 screwed together with 5 screws (3 on one side, 2 on the other). The pieces measured 39 inches.

After that, I drilled pilot holes on both sides (centered and 1 3/4 inches in). Into these pilot holes, I drove galvanized lag bolts (with washers) using a ratchet with the appropriate tip.

Driving the lag bolts in ahead of time will make it easier when attaching them to the posts.

Step 8: Building the Barrel Braces

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For a two-barrel system, I needed to make four of the barrel braces.

This is what a finished barrel brace looked like.

All four of them measured 39 inches apiece.

Step 9: Installing the Barrel Braces

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The bottom front barrel brace went in first.

I drilled pilot holes into the posts where the barrel brace was to go. The pilot holes were exactly 13 inches up from the ground.

I drove the lag bolts the rest of the way with a ratchet, making sure to check with a level.

Step 10: Installing the Pole Braces

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The bottom two pole braces went in next.

They went in directly under the first barrel brace and were screwed in after being checked with a level.

These offer nothing by way of support for the barrels. All they do is help to maintain structural stability on the frame.

Step 11: Installing the Barrel Braces

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Next, the second barrel brace went in. These two will be what supports the bottom barrel.

The pilot holes that I drilled to accept the lag bolts were 23 inches from the ground.

The difference in height makes the barrel tip slightly forward. The angle helps to fit more water in the barrels as they fill and allows the barrels to drain more completely.

Step 12: Installing the Barrel Braces

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I tested the bottom braces with an empty barrel to be certain that the barrel would fir properly.

Step 13: Installing the Pole Braces

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Aftet that, I cut out the top two pole braces.

The top pole braces will go on the same angle as the barrels, so it is useful to measure to determine the appropriate length.

Mine were 38 1/2 inches.

Step 14: Finishing the Frame

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The last two barrel braces and the last two pole braces went in next.

I drilled the pilot holes for the top two barrel braces exactly 25 inches up from the tops of the bottom barrel braces. I drove them in with a ratchet and checked with a level.

The ends of the last two pole braces went up exactly 26 inches from the tops of the top two barrel braces and are held in with screws.

Step 15: Finishing the Frame

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This is what the finished frame looked like.

Step 16: Finishing the Frame

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I then tested the frame with two barrels to be sure that they both fit comfortably.

The bottom (and heaviest) barrel is slightly pinched in by the top barrel braces. This adds to the stability of the bottom barrel.

Step 17: Finishing the Frame

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With the two barrels in their final places, I attached additional barrel supports in the fronts and backs of the barrels. All four supports measured 39 inches.

I checked the supports with a level, but did not take an exact measurement of their position. They were placed where I felt that they would support the barrels best.

With the four barrel supports in, the barrels are in their final positions and can not slide backwards or forwards.

Step 18: Installing the Barrels

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I chose to use barrels with raised lips on the top.

Into the lip of each barrel, I drilled two screws down into the barrel braces. This will help to prevent the barrels from rocking and shifting during bumps or windy days.

Step 19: Installing the Plumbing

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I used a barrel wrench to screw the plugs into the barrel bungs.

The plugs that came with the barrels were already threaded to accept drains and other attachments.

The very top bung did not get a plug as this is where the drain will go later

Step 20: Installing the Plumbing

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This is what I used to connect the barrels.

My barrel plugs came already threaded to accept various attachments.

I chose these hose bibs because they were a little longer than a standard boiler drain or hose bib. However, most anything would work. To make them fit the plugs, I also needed to use a bushing to adapt them.

Wrap the threads with thread tape and snug with a wrench.

Other parts can be substituted at this point, such as two pipe elbows instead of hose bibs.

Step 21: Installing the Plumbing

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These are the barrels with the hose bibs installed.

Note that the middle hose bib is upside-down to accept the connector hose.

Step 22: Installing the Plumbing

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I made the connector hose out of clear tubing and two female hose ends.

The hose ends were in the garden department as replacement parts for mending broken hoses.

Make sure that the hose ends properly fit the hose bibs when shopping for parts, otherwise additional adapters may be needed.

Step 23: Installing the Plumbing

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This is the completed connection.

With both hose bibs in the fully open position, water will be able to drain from the top barrel into the bottom.

Step 24: Testing the System

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At this point, I decided it was a good time to check for leaks. I filled up the system through the top bung and waited to see if any water leaked out.

I did notice that the top plug was dripping, so I tightened the plug a little more and all was fine.

Step 25: Testing the System

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I then tested all the hose bibs to make sure they worked properly

Step 26: Testing the System

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I attached a garden hose to test if I was getting an acceptable amount of water pressure.

There really is no pressure to speak of, since this system is gravity-fed, but the barrels should be installed high enough to get a constant flow of water.

Step 27: Testing the System

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Next, I drained the system and washed it out an additional time to be certain that I flushed out any small debris.

Step 28: Installing the Drain

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Anybody attempting this may want to consider installing gutter guards like this.

They help to keep debris from clogging the system by just allowing the water in and dropping debris from the roof.

Step 29: Installing the Drain

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Detach the gutter and measure the width of the spout.

You will need to know this when shopping for parts.

Mine happened to be two inches.

Step 30: Installing the Drain

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These are the parts that I used to drain water from my gutters into the barrels.

I used a 2 inch to 1 1/2 inch rubber reducer and various pieces of 1 1/2 inch ABS pipe.

The bungs on the barrels are 2 inches wide and the extra half-inch is to allow water to drain out when the barrels reach capacity.

Step 31: Installing the Drain

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This is the new gutter drain.

The reducer was clamped on to the spout and the ABS pipe clamped in.

This is what all of the pieces will be built off of.

Step 32: Installing the Drain

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Dry-fitting all the pipes and various fittings is useful to determine exactly how a drain will be put together.

A person attempting this may want to experiment with what works best as not every setup will need the same parts.

Clean the pipes and fitting and apply ABS glue to cement into place (those using different types of pipe such as PVC will want to use the appropriate type of cement as well).

Step 33: Installing the Drain

Picture of Installing the Drain

Make sure the pipe fits and rests comfortably on the barrel. Also, I used a piece of wire nailed to the barrel brace to hold the new drain in place.

You will want to use piping that is less than the size of the bung, otherwise water will not be able to leak out and will back up your gutters, potentially causing flooding problems for a basement or crawlspace.

An optional thing I did was to select a 90 degree bend with an additional outlet. Into that, I cemented a thread and cap. This will act as a temporary override during a storm if the system were to become clogged with debris and cause the gutters to become backed up with water. Simply remove the cap and the excess will spill onto the ground.

Step 34: Installing the Drain

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This is the completed drain.

Note that it is simple with the least amount of parts used and rests comfortably in the barrel.

Step 35: Finishing Touches

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I used a reciprocating saw to cut the tops of the posts off, using the top pole braces as a guide.

Step 36: Finishing Touches

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I then screwed on the roof to the frame.

The roof measured 45 x 45 inches of 1/2 inch plywood.

Step 37: Finishing Touches

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This is the completed system.

All the instructions from this point on are pretty much optional, since the decoration is up to the builder.

Step 38: Decoration

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I chose to remove the roof and hang plastic lattice on the sides and back and used 1 1/4 inch finishing nails to hold it in place.

Step 39: Finishing Touches

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I began using a reciprocating saw to trim the lattice, but later switched to a hand saw because it made more even cuts.

Step 40: Finishing Touches

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I re-attached and shingled the roof to protect the plywood and make it more attractive. I used 3/4 inch roofing nails for this step.

Step 41: Finishing Touches

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This is the project completed.

However, I would like to paint the wood with a low- or no-VOC exterior paint at some point to match the house.

Step 42: Final Thoughts

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This is it.

A few final thoughts:

  • The hose that drains from the top to the bottom barrel would benefit from being wider. Water can only pass through as fast as the smallest opening can handle. If I were to re-do it, I'd try to drill or cut a wider hole to accept wider fittings and tubing.
  • There is most likely a way to pressurize the system with an air compressor for applications that need more pressure than gravity such as sprinkler systems.
  • The bottom barrel would most likely benefit from a small hole drilled above the water line to let out air as it gets replaced with water. This will allow the top barrel to drain into the bottom barrel faster and at a more steady rate.


cleflaive (author)2015-09-08


I did more or less the same project, but with a (I think anyway) much simpler approach.

Thanks for sharing

crickle321 (author)cleflaive2015-10-26

That's a pretty good looking setup.

Captmickeyd (author)crickle3212017-06-27

I think the advantage of ipodguy's setup is additional water pressure due to the height of the rig.

SabinaCowan (author)2015-09-09

What about stacking the barrels upright on top of each other instead of lying them down?

Zaryn (author)2011-07-03

Why two pieces of 2x4 instead of one piece of 4x4?

ToryB (author)Zaryn2015-09-08

also worth noting, 2 - 2x4s fastened together provide more strength then a single 4x4. This is due to the different grains allowing the different pieces of wood to make up for the weak spots in the others.

Foehammer358 (author)Zaryn2012-01-05

It's quite a common trick. 4x4s are much more expensive than 2x4s, and 2x4s are more common. In this case it might be to sandwich something in between them.

hitachi8 (author)Foehammer3582014-09-26

here they are the exact same price, its just that sometimes the lumber yard dont have the correct lenth.

robert.latterman (author)2015-09-06

Great project... !!! Think restrictions may take over after a while... but hope not...

CLEM2 (author)2014-12-14


davidbarcomb (author)2014-11-23

Nice project. Thanks for sharing

Handsome-Ryan (author)2009-06-03

Are you not concerned with algae growing in the clear tubing?

iPodGuy (author)Handsome-Ryan2009-06-28

Didn't even think about it until after the fact. I still use the clear tubing and I have a little green growing on the sides and I suppose that if it clogs then since it's so short, I can just ream it out with a stick.

hitachi8 (author)iPodGuy2014-09-26

you could add a little lime or ash to your water from time to time.

that will fertilize and stabilise your plant and kill any mold growing at the same time.

yoshhash (author)iPodGuy2009-07-01

woah- why is this particularly an issue with clear tubing? I have a greywater system with some clear tubing, this did not occur to me either. I bought it only because that was all they had at the store I went to. Yes, very nice instructable. I really like how you tipped the barrels to take advantage of the built in threading- this is a particularly sore point with me, I would love to see an instructable on how to install leakproof spigots on a curved surface. I have a method, which I will soon be posting, but I'm still waiting to see if it holds- want to see what others have been trying.

iPodGuy (author)yoshhash2009-09-03

Algae buildup is typically only an issue with clear tubing because algae is a plant that requires photosynthesis to survive. The darkness inside of an opaque piece of pipe or hose prevents light from entering, therefore reducing algae's success of growing there. I too am interested in seeing other's ideas of installing leakproof spigots on curved surfaces. Especially ones that don't involve cutting the top of the barrel off to allow the builder to reach inside.

Paladin (author)iPodGuy2010-04-22

 Yeah, maybe go with the black poly tubing instead. Excellent instructable though!

mjtc98 (author)Paladin2011-06-16

Or 'retrofit' your clear tubing with a little paint :)

Paladin (author)mjtc982011-06-16

Nice idea, but not too many paints will stick to the clear tubing and remain flexible. The black poly pipe is cheap.

gkten (author)2014-05-16

Hi nice work. Allow me to say that you may need to add some kind of filtration. I see that your house is below trees and the pipelines could be blocked by leaves.


canman200 (author)2014-05-11

Top idea already gathering the material for this build.

dudaott (author)2014-05-04

Great Instructable! To solve the flow problem from top to bottom, you can drill a little hole at the upper back of the lower barrel and connect it through a hose to the upper part of the top barrel. And I think it's a good idea to put a simple one-way valve in the inlet of the top barrel - i.e. the entrance of the rain water. This way you can prevent the water to try to come out from the top . And you can add a simple filter system in the down pipe. I know I have a picture somewhere around here... I'll keep looking and post after...

qwerty924 (author)2014-05-02

i might make something like this for the animal pen in my back yard. this would make it so much easier to water them if the water was readily available but your idea of putting a hole in the bottom barrel is a very bad idea. because there is still water above the water line of the bottom barrel there would be enough pressure to allow water to escape through that hole. if you put a valve on it then it might work though

mganpate (author)2012-07-01

how to filter the rain in fast rain coming so its very dirty?

DanCrocker (author)2012-03-26

Maybe reduce the angle a bit? You wouldn't need much to ensure a flow to the front. Just a few degrees.

DanCrocker (author)2012-03-26

Something like this LobosSolos?

DanCrocker (author)2012-03-26

Again, not meaning to be critical here but I think I would have used nuts and bolts with large washers to distribute the load instead of lag bolts - which would have a tendency to sag over time given the weight. But then, I am no engineer. ;p)

DanCrocker (author)2012-03-26

Hadn't thought of that. Good idea.

DanCrocker (author)2012-03-26

An alternative to using lag bolts would be to drill all the way through the post and use nuts and bolts with large washers under the bolt head and nut. These could be tightened as needed as the wood ages.

sunshiine (author)2011-09-04

You really spent some time on this ible! Thanks so much for sharing your hard work!

Discojess (author)2009-02-05

This is amazing. I've been planning to put a system in, this one is very attractive. I was also wondering about the air hole situation, so, as you have it, the air I'm assuming just escapes through the gutter? Also, if you drilled a hole in the top of the bottom barrel, would it then squirt out of that hole once the top barrel starts to fill, since the pressure will be coming from higher than the hole? maybe some kind of a hose that goes from the air hole to above the highest barrel... this is awesome.

iPodGuy (author)Discojess2009-02-06

Not quite. The air escapes through the very top bung. There is about 1/4 inch clearance with the inlet pipe and the top bung. The air comes out of there as well as extra water. So, the only thing the gutter does is divert the water to the barrels. I guess if you put a hose from the top edge of the bottom barrel to the top edge of the top barrel, it would cause the bottom one to fill more. It's not something I'm going to try however since it already saves me enough. If you are really concerned with getting every single possible drop, then try making a system with upright barrels.

jeffeb3 (author)iPodGuy2011-05-19
Upright barrels is a good idea. Keep in mind, that no matter what the shape of the container, the final pressure of a gravity powered tank is proportional to the depth, assuming no resistance in that hose. So a vertical system could possibly be much more pressure.

For your implementation, you can just add a hose from the top-back of the bottom barrel to any place in the top barrel (it doesn't have to be in the upper bucket air pocket). This will serve two purposes 1) allow water to fill in the upper part of the bottom barrel; 2) increase the amount of flow from the top barrel to the bottom.

Great instructible, I know it's old. I'd be interested in you updating it with a follow up.

I plan to buy a couple barrels, and then convince my wife to let me do something like this.

iPodGuy (author)jeffeb32011-05-20

Thanks for the comment.

What would you like to be updated on?

tarchambault (author)2011-05-10

I stumbled upon this project a few weeks back, and since then i have convinced the garden club and my children's school to install this in our community garden.
We had the barrels donated to the school and plan on getting it built within the next week!
This is just such an excellent idea! Thank you for sharing it!

tyoungman (author)2011-03-16

just wondered why you angled the barrels. what little water you gain on one end you loose on the back

mikesnyd (author)2011-01-07

awe come on man.. where is the gutter and debris gaurd on this small roof lmao. great little build man!!

mikesnyd (author)2011-01-07

maybe not a decoration but maybe a sealer could be used on the roof of yours. unless it all is already treated wood.

plumber4 (author)2009-09-11

Here is a tip that was suggested to me years ago while installing a wood fence around our garden. I found it very useful. Try digging smaller diameter holes and using pea gravel instead of cement. The pea gravel is a bit more expensive (which is why i suggest using smaller holes, you use less gravel). but has a few advantages over cement. 1. Better drainage - this also means longer life of the wood posts. Place a few inches of gravel in the bottom of the post hole. This allows for better water drainage. Your posts will take much longer to rot and will likely outlast the structure above ground. 2. Strong yet easily removed - Posts that are set in pea gravel can be removed without digging and with little effort. Posts that are cemented in are pretty much permanent or at least very difficult to remove. If you decide to move, you can easily take your water harvesting system with you. 3. Less work - mixing cement can be a lot of effort. If you are not not familiar with mixing, it can be very difficult to get the desired mix. 4. Time saving - The time saved by using gravel is well worth the few extra bucks that you may spend on gravel. Also, you do not spend any time cleaning up the cement mess. After getting your post true, fill the hole around it with a few inches of pea gravel at a time. Pack the gravel down with whatever you have (i use a small section of thin lumber or a 2x4. Keep doing this until you are a few inches from the top of the hole. Then use earth to fill in the rest. Tamp the earth down and its set. This ends up looking better than cement as well. Of course always be sure to dig your post holes far enough past the frost line. In Lower Michigan, 42" is the depth to dig to.

mikesnyd (author)plumber42011-01-07

I never thought of using pea gravel as the base before. I like it. I would do one thing a little different. I do some fiberglassing and usually have a bit of polyester resin laying around so its nothing to me to soak the ends of my posts with a quick coat of resin. No fiberglass needed. Once soaked they don't absorb moisture. And man does your wood last.
I have never in my life dug a hole more then 36" and never had a problem... but thats for decking and such. I usually only have done 24" and use concrete. For a fence being more linear (unlike the box we are making here) and having to deal with mother natures winds 42" would be cool for the pea gravel method.

LobosSolos (author)plumber42010-04-23

You can also put the concrete in dry.  As it rains it sets up and you don't have the issue of the concrete pulling away from the post as it cures.

iPodGuy (author)plumber42010-04-22


becca-boo (author)2010-05-26

Technically, water is not a renewable resource. Water is not created (like trees and other renewable resources) but recycled. But Im just busting your chops, this thing is amazing! My dad was looking for a way to create his own rain barrels and this is just the thing! However, i must agree with Donron, It seems there is no way for the air to escape once the barrels begin to fill with water. (of course it is very possible i missed a step where you mention to drill an air escape hole or the barrels are already equipped with such a hole) None the less, this idea was brilliant.

wmcross123 (author)becca-boo2010-12-03

Where do you get the barrels?

BeeRich (author)becca-boo2010-08-20

Actually, water enters and leaves cellular systems all the time. I like this project.

iPodGuy (author)becca-boo2010-05-27

Yes, I think you missed a step.  The air in the bottom barrel will go to the top (not extremely efficient, but that's what it does) and the air in the top escapes from the gap in the topmost bung.  That's also where the excess water leaves from.

becca-boo (author)iPodGuy2010-05-27

 Oh, I see. ha ha. I guess I did miss that step.

donron (author)2010-05-03

 hello.i think that your barrels will never be full of water.this is because you didnt put them the upper part of the barrel there is no way of air going out and it will just stay there decreasing the water holding capabilities of your barrels.if you put them in the same way but with the openings of the tubing in the upper side they get filled properly.

iPodGuy (author)donron2010-05-27

I know they don't.  I covered my reasons for doing so in the instructions. 

markallan (author)2010-04-29

Are you sure the stand-ends will hold the weight of the barrel onces they are filled with water?



About This Instructable




Bio: Just your average handyman.
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