My friend and I were discussing this topic, and I vaguely remembered a dish type thing that collected dewdrops or something. Anyone here know of cheap, DIY ways to achieve this?
Dig a hole. Put a cup in the middle. Put a piece of plastic or tarp over the hole so that it dips in the middle. Punch a hole so water condensing on it drips into the cup.
You don’t get a lot of water by any means but it works if your in the wilderness and in need of water.
This sounds more like a solar still, in your usage you don’t need to punch a hole nor a cup, the water will pool there in the tarp all by itself. Though the cup could be useful in catching the water from the other side.
dew is water that has condensed on objects that cool below the dew point. this happens when heat is lost from those objects at night. a humid clear night will have dew form on surfaces and run down hill. a rain gauge can collect enough liquid to give a reading of 0.01 to 0.04 inches even though no rain has fallen.
Here’s an article from New Scientist.
Doesn’t look like it needs specialized materials, but I think the “canvas” is a really smooth sheet of plastic. Would color matter? You want it cool off as quickly as possible at night.
None of these were exactly what I was thinking of, but all interesting… 
a dish left out overnight, on a humid and clear sky night, that especially if isolated from the earth surface (so that it cools) might get a small amount of water collected in the middle.
This is done on a larger scale in Peru.
The cleanliness of the water you get is going to depend on how pollute the local atmosphere is. However, even at the worst you should get some fresh, reasonably drinkable water.
Now that is cool!
What you really need is a droid who understands the binary language of moisture vaporators.
Thorny devil lizards do this with their own bodies.
What were you thinking about?
Probably one of the easiest ways is to drag a rag over something that does get dewy (the grass, a car) and wring it out into a container. But collecting dew is mostly for emergencies. I doubt most people could get enough to make it worthwhile, at least not without filling their yard with contraptions. Depending on location and climate/seasons, there may be days or weeks where there is little to no dew.
Same with Darkling Beetles - video clip here.
I needed that - thanks for the giggle.
Related to trapping dew is getting moisture from plants and trees. Cut off a small branch or two, then wrap a plastic bag or something around it. In addition to collecting the dew that will accumulate on the branches and leaves you have in the bag, some moisture will leak out of the end of the cut branch or stem as well.
Happy to help. 
remembered this from a buz sawyer strip (when they got stranded in the galapagos.) i’ll add that you don’t have to punch a hole, just weigh the tarp down with a small rock at the middle to form the dip. then you must have a hose or plastic tubing attached to the cup to allow the user outside to tap the collected water.
a plastic sheet placed over a hole in the earth weighted with a rock in the middle will if no hole in the plastic collect in a cup evaporated and condensed soil moisture.
a plastic sheet placed over a hole in the earth weighted with a rock in the middle will if a hole in the plastic collect in a cup condensed dew from the air above over night and get soil moisture.
the purpose of the set-up is to collect water from the soil sub-surface, not dew. putting hole will collect dew outside alright. but it’ll be easily contaminated by dust and other extraneous matter. keeping it tightly closed will minimize contamination.