In a previous blog “Milking A Tree For Water” I wrote about the phenomena of transpiration and how to collect water by covering the end of a leafy branch with a plastic bag. This article explains a different approach using the same principal but by covering grass with a sheet of plastic.
I decided to simulate an emergency scenario by improving a condensation surface by cutting open a 16 gallon sized plastic bag to spread out as a sheet measuring 2.5 feet by 4 feet. Because of it’s thin material and flimsy nature, the slightest breeze could blow it away so I weighted it down with small stones at the four corners but it still fluttered with the breeze. That fluttering could spill any collected condensation back into the grass so I placed more stones around the edge until it was still.
I left this moisture collector alone for about a half hour then returned to find it holding a “beady” fog on the bottom surface. The first step in collecting this moisture was to protect it from touching the grass so I removed most of the stones including one at the corner. I pulled that corner of the sheet up and back until the entire sheet was completely inverted and laying flat on the grass. Then I gathered all corners together and lifted the sheet upward, thus consolidating the beads of water into larger drops that flowed down into the center of the sheet, forming a small puddle. I continued to tap the sides to consolidate all of the droplets into the bottom and then I carefully poured the puddle out the side and into a measuring cup (see picture insert).
Under the environmental conditions of the day combined with the size of the sheet I was able to collect about an ounce of water. Your results may vary. Larger sheets with greater surface area will yield larger volumes of water. It would be strategic to set out a number of sheets at the same time to increase the total yield of harvested water.
Subsequently I have used a thicker plastic sheet that I found much easier to control during the entire process. This would make a great weekend project that would familiarize you with the process and give you “hands-on” experience.