STAND-ALONE RAINWATER COLLECTOR


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Categories: Rainwater Harvesting

By  found via Instructables.

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.

FEATURES

> First of its kind on instructables
> Independent rainwater collector
> Easy DIY solution
> Standard parts
> Affordable (€ 70 or less)
> Reused/recycled materials
> Lightweight (> 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.

Step 1: REQUIREMENTS

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 ]

TOOLS

· 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

NOTE
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.

NOTES 
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.

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