The procurement of water during any apocalyptic/disaster event will be one of your top tasks. As with many of the creature comforts civilization affords us, you may be in a situation where clean, running water is simply not available. In this situation, a solar still is a smart choice.
Side note: Given how many situations it comes in handy, adding a sheet or two of strong, transparent plastic tarp material to your emergency kit or bug-out bag is usually a good idea.
For making a solar still, you will need -
1. A pot or cup device for water collection
2. A sheet of clear plastic or a semi-transparent plastic bag
3. A rock

You will need to dig a hole in the ground, 12-24 inches deep and a few feet around. You will put the pot in the hole face up so that it can collect water. Place the sheet of plastic over the top of the hole and anchor it in place. Put a rock or other small, heavy object on top of the plastic, above the cup in the center of the pit.
As water evaporates, it will collect on the top. Putting a rock in the center of the tarp weights it down, making a “V” shape. This causes the condensed water on the tarp to collect and drip down into the pot.
If you are unable to dig a hole or are otherwise unable to build a solar cell, all is not lost. If there is vegetation in the area and you have some plastic bags, you can tie these around a tree branch and collect small amounts of water. However, it will probably be even less water than a solar still could provide and take longer as well.
This method of water collection often works better at night. Make the solar still as large as is practical in order to collect more water. Plastic must be steep enough to run into the collection cup (and not drop), and the plastic must not touch the pit soil in order to maintain sanitation.
Pro: You can also put unclean sources of water (such as urine, salt water, contaminated/stagnant water) into the pit (not the drop-collecting pot!) and use the solar still to purify it. Any water that results from the solar still process is going to be purified via the evaporation process. Also, you can set up as many solar stills as your resources allow for increased water production.
Con: The downside of this contraption is that it can be slow and ineffective when employed in a dry climate. It can supplement your water intake, but may not be enough on its own to meet your daily water requirements. Read more »