We are students industrial design and for the past 2 weeks we have been building a rain harvesting system. Our client is a community with a public garden because they don't have a private garden for themselves. The garden is a place where they can cultivate some vegetables and fruits, relax, enjoy the sun, have a BBQ and meet new people. They don't have a water supply, only a 1000l reservoir that’s filled a little every week by the city. If the city decides to stop filling the barrel they can’t water their plants on hot days. This is why we created a stand-alone rain catcher.

Our design is like an flexible inverted umbrella. It's a stand-alone rain collector independent from the water network, trees and/ or roofs. Our product gives the people rainwater, shade and a place to have a chat with eachother. The reservoir on the bottom stores the water and is made with a tabletop so people can gather round the rain collector and have a beer, while standing in the shade or out of the rain.


> First of its kind on instructables
> Independent rainwater collector
> Easy DIY solution
> Standard parts
> Affordable (€ 70 or less)
> Reused/recycled materials
> Lightweight (<10 kg)
> Flexible (won't break)
> Suits environment
> Added value (standing table/parasol) 

!!! WARNING !!!
- Make sure you do not break any local laws, concerning height, rain collecting,...
- The water is not potable! Only use it for watering plants. Their might be toxins from the canvas ending up in the vegetables so make sure you use a 
not-soluble plastic.
    (If used for drinking water, you need to make sure the canvas and barrel do not contain any toxins and use a good filter.)
- Depending on the canvas you use, UV can impair the canvas.


MATERIALS      [ € 70 ]

· 1 PVC tube - large Ø (80 - 150 mm) - length: 2 m      [ € 5,60 ]
· 4 PVC tubes - small Ø (25 - 30 mm) - length: 3 m      [ € 8,40 ]
· 8 Tube snaps - Ø 25-30 mm      [ € 1,60 ]
· 20 Nuts & bolts - M5 x 30      [ € 3,40 ]
· 8 Eyebolts & Nuts - M5     [ € 7,00 ]
· 60 m clothesline      [ € 5,40 ]
· Tension Straps - 5 mm width      [ € 2,50 ]
· Metal straps - Ø = large Ø + 2x small Ø      [ € 3,60 ]
· 4 Keyrings      [ € 1,49 ]
· Net (for a pond) - 3 x 3 m      [ € 5,80 ]
· Impermeable fabric, canvas (7x3 m or 2x 4,5x3 m)      [ €11,10 ]
· 16 cable clamps      [ € 6,54 ]
· Table top plate (preferably PVC / natural wood)      [ reused ]
· 6 shelf supports ( L )      [ € 4,50 ]
· 1 industrial reservoir - 1 m³ / 1000 l     [ reused ]


· Drills
· Handsaw
· Pincers
· Scissors
· Screwdrivers
· Marker
· Measuring tape
· Sewing machine
· Duct tape
· Ladder
· Someone to help you

With the formulas below you are able to roughly calculate how much surface you need.

Plants                      20 l/m² per week needed (average)
Garden space         GS
Rainfall (average)   17,5 l/m2 per week (local weather site)
Surface needed      ( 20 l/m² x GS ) / 17,5 l/m² = collector surface needed

The maximum surface of one collector is 6 m² (restricted by standard lengths of tubes max 3 m) . If you want to go bigger, we suggest that you build more than one. When you go for a smaller one, you should scale down the sizes and distances. But never the amount of pieces needed.

Step 2: CENTRAL TUBE ( Ø 80 - 150 Mm, 2 M )

Drill random holes in the bottom meter of the tube, this will help the water flow into the barrel and acts as an extra filter.
Now drill 4 holes on every quandrant of the large tube at 1,2 m from the bottom and another 4 at 1,5 m from the bottom.
Make sure the distance between the holes is the same everywhere.
Attach the tube snaps ( C ) on the holes with bolts.

Drill the hole with a drill size that's 0.5 mm smaller than the diameter of the bolts you're going to use (self-threading).
Use countersunk bolts to make sure the bolt is secured in the pvc snaps. Otherwise it will be difficult to snap the tube into the connections.

Step 3: SMALL TUBES ( Ø 25 - 30 Mm, 3 M )

The 4 PVC tubes are the same.

Drill a hole through the pipe at about 30 cm from the start of the tube and another at 2 cm from the end.
Now rotate the tube 90° and drill another hole at 50 cm from the start of the tube.
Attach the eye bolt on the 30 cm and 2 cm holes.
Now snap the small tube onto the large tube, eye bolt turned outside.

Repeat this for the other 3 pipes.

Connect the 4 pipes by putting tension straps through the 8 holes at 50cm from the start. This will keep the pipes from turning around too much. Also attach metal straps around the pipes for extra strength / safety.

Step 4: CANVAS

Cut out the canvas pattern (drawing) four times. For smaller models you can downsize it. Make sure you have a hole in at least 1 top corner of each part.

Sew two pieces together on both blue and red line (for the tube sleeve). Repeat this step three times until you have the four patters sewed onto eachother. Now you should have the funnel on the inside and tube sleeves on the outside.
If you have remainings of the fabric at the sides, you can cut them off.

Put the fabric funnel onto the structure. Make a hole in the 4 flaps on the bottom of the funnel. Lace these holes together using the clothesline and attach it to a brick - or other weighty object - and drop this in the central pipe; this will guide the canvas into the central tube and keep it there so the water will flow into it.

When the canvas is attached onto the frame, you can screw the eyebolts back into the end of the small pipes. Make sure they face the same direction as the ones at the bottom.

Use a strong needle (for jeans) because the fabric is quite tuff to stitch.
A double stitching line / pattern is recommended!

Step 5: WIRES

Cut 4 wires at the length of 3,3 m and 4 at the length of 4 m.
Use the clamps to make a loop, the loop-to-loop should be about 3 m.
The 4 short wires are used for the square, rain catching, surface on top.
The 4 long wires are used for anchoring the whole structure to the ground.

Next step: take 4 key rings and attach them each to an eyebolt at the top of the small PVC tubes.
Attach the metal hole from the canvas to the ring in each corner.

Connect the 4 corner rings onto each other, using the 4 short wires (3 m) to become the square surface.
Connect the 4 remaining wires (4 m) to the ring in every corner.

Stretch the net and cut it to size 3x3 m.
Connect the corners of the net to the rings on every corner.
After this you can attach the sides of the fabric and the net with the wires, using tension straps.
You can make some holes in the upper side of the canvas for the tension straps.

Now pull the flexible catcher open until the fabric is under tension.
Then anchor the long wires (4 m) into the ground using pickets.

If the wires between the 4 small PVC tubes are too loose you can adjust the length until it's under enough tension.

Step 6: COVER

Take the cover from the reservoir and make a hole in the middle with about the diameter of the central pipe.
Attach 3 shelf supports ( L ) around the middle hole (every 120°). These will keep the structure straight into the barrel.
Use the same nuts and bolts as in step 2.

Mark and attach the shelve supports onto the cover with the central PVC tube already in place. Because of this the pvc tube will fit exactly between the shelve supports.


Now make a table top at about the size of the barrel (1x1,20 m).
Make a hole in the middle of the plate that has a little larger diameter as the central pipe so the shelve supports can pass through.


Put the barrel in place. Screw the cover on and place the table top on the barrel.
Fix the tabletop with tension straps to the barrel. You will have to drill some holes into the table top, close to the frame around the barrel. Place the tube in the barrel and pull at the wires at each corner.

Once the barrel is in place, you can attach the wires to a picket and fix them into the ground.

Now everything is set up, you're ready to harvest some rain!

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    46 Discussions


    5 years ago on Introduction

    This is a great idea---and worthy of improvement. One important thing---the plastic of the IBC MUST be protected from the sun---otherwise it will deteriorate and eventually crack---AND it will soon start to grow algae wherever the sun strikes it. This is guaranteed and becomes a nuisance.So the best thing is to build a cheap plywood covering for the IBC. This idea is nice since it does not require a roof. Often when you capture water from your roof, you are forced to make an ugly addition to your home. This could be free-standing out in the yard--and serve other purposes as well. Here's an idea----sink it partially in the ground, put a nice oversize top on it, and it can serve as a patio table! Then you could put some chairs around it and voila---you have a cool place to have lunch.....Hmmmmm---Now that I like----and maybe I will make one.....

    1 reply

    Reply 2 months ago

    If you sink it partially in the ground how would you get the water back out, as the faucet is at the bottom? I'm just curious because I have a raincatcher very similar to this one. I have an ibc tank and a tarp to catch the rain. I cut some small unwanted trees down in my yard and turned them into my frame. Zip ties them together and zip tied my tarp on my poles. Cut a hole in the tarp, put a screen on it and attached it to the opening on the top of the tank. The rain filled my tank up in no time. I put a pump inside the tank with a hose attached and pump water into my house. Great toilet and shower water.


    1 year ago

    Really great work guys. Came across your system on Pinterest.


    5 years ago on Introduction

    If you're in the US, be careful that you aren't violating (dumb) rainwater collection laws. I know where I live, you need a permit to collect any rainwater.

    5 replies

    Reply 5 years ago on Introduction

    that's a good point, swindle2. Even tho the state laws (on the referenced web site) would permit this, my municipality has regulations that would prohibit this, specifically that the source is not the roof of an existing building. The city also limits us to 450 gals (IBCs are generally 275 or 330 gal). Adding wheels to this design, being portable rather than permanent, might circumvent those local laws... IANAL. Moving a ton of water on unpaved surfaces might belie that portability, but that's my story and I'm sticking to it.

    It also depends on the type of "wheels" used to aid that portability.
    I also agree, if I can add my two cents worth, with most of the posters regarding the warnings. There are those who have NO common sense, and I sometimes wonder how they even survive!

    With a collection roof that looks like a large colorful flower, a larger table area, this would look really cool in a small backyard.


    5 years ago on Introduction

    Wondering about an adaptation to this great idea that would include a solar distillation unit for purification of the water to make it potable. Going to have to get in the workshop with this one :)

    2 replies

    Reply 4 years ago on Introduction

    If you live in the country you are guaranteed to have a very pure water, I'm not sure if distillation is a good idea because you would be removing minerals from a water that already has a very small amount, and a water without minerals would be dangerous.

    I know people who has lived many years on rainwater collected from their roofs (clay tiles) and stored in concrete tanks, they often throw a bit of bleach to kill the bacteria and maybe a small filter but that's all.


    Reply 5 years ago on Introduction

    As someone who has lived on tank water for over 20 years, I reckon it already IS potable :o)


    5 years ago on Introduction

    Great concept guys/girls, i'm seeing some possibilities with materials that are easy to obtain where I live. I'm considering what Fyodor said, while I don't live in Nevada, (but will definitely take one if I go to Burning Man again) in many places wind and rain go hand in hand. Thanks for sharing your project with us!


    5 years ago on Introduction

    Nice design but I think there could be a better material than plastic it will deteriorate in the sun(releasing toxins into the water) and weather and also flap about noisily. What would be better would be maybe fibreglass with a protective resin coat they use on roofs. Fibre glass is a wonderful material for getting a strong thin weird shape. I've also seen instructables on concrete roofs with special mixes although maybe these are too permanent depending on your purpose and the legal restrictions. The fibre glass could be either affixed to a plywood/chipboard frame (just coat it completely and it will last forever) Or directly to the top of the plastic if you pull it really tight. Another option would be any normal roofing material...tiles, felt, corrugated iron although all these save the first have draw backs.


    5 years ago on Introduction

    really neat idea,..tom hanks could have used that on his island. Here in S. Nevada the sun and wind would beat that tarp up in no time,..I think I'll make it auto open/close with arduino and water sensor.


    5 years ago on Introduction

    Great idea but you need to know that the type of tarp/canvas you used is treated with water repellant at the factory and is not suitable for potable water / human consumption. You might want to make a big warning about that. The water repellant stuff is also a persistent pollutant which builds up in breast milk, organisms and the environment. Perhaps consider a different canvas. That aside, I like the design.

    2 replies

    They clearly have intended this to water plants. They don't need to put a warning to prevent people from drinking out of the toilet either.

    If they are in school for industrial design then they will be learning about material selection which requires research and knowledge about safety and health requirements. Any good design instructor would point this out in a critique. Sometimes you have to consider unintended uses and kids sure like to drink from hoses so I don't think my comment is out of line. It was meant as a constructive critique intended to help create a better product. Cheers.