1 millimeter of rain x 1 meter of surface area = 1 liter of water.
This rain catcher is a two square meter sheet of plastic folded in half, so for every millimeter of rainfall I get a liter of water for my garden.
1 x 2m sheet of plastic or a size to fit area
2 thin battens to form the water channel
Synthetic string to hold battens together and to fence
Optional: wood to secure plastic to top rails
Step 1: Start With a Square of Heavy Plastic …
Fold it in half on the diagonal.
Step 2: Tack It to a Fence Corner
To make the plastic form a “V” to channel the rain, pull the square corner of the plastic over the corner of the fence as shown in the diagram.
Option A: Tack the plastic to the top fence rails
Option B: If you are in a windy area, nail battens to to the top rails to hold the plastic in place. My rain catcher wouldn’t have lasted the night without the battens.
Trim the excess plastic off.
Step 3: Add Battens to Form a Rigid Channel
The battens help hold the plastic down especially in a breeze.
Cut two pieces of thin wood the length of the diagonal of the plastic and about 25mm (1") or slightly wider.
Drill holes on each end.
Tie the battens together on one end.
Slip the battens around the plastic.
Tie the other ends to the corner of the fence.
Step 4: Place a Bucket Under the End of the Battens …
… and get ready for rain to fill the bucket. Every 20mm of rain fills a bucket.
I'm sure there is a more elegant solution for storing the water but so far I rotate a couple of 20 liter buckets and tip the full one into a watering can.