[Screaming Eagle]

You're in an area that you're not familiar with (just to take away the comfort zone for this scenario). You've got a light backpack with your typical supplies (including Altoid tins) and your canteen ran out yesterday. Maybe a handgun. Certainly a good knife.
You know that water is top priority. No snow available. No standing water from recent rains. Woods and hilly region.
How do you find water that has not been stored (as in an abandoned cistern) to make it through the next few days?
My initial suggestions:

Watch the birds. If they're flying high, they could well be looking for water since they need it 2x daily in most cases.

Look for unusually green foliage especially from a high place if possible. Willows, cane, reeds, maybe large vines all use large quantities of water that could be accessible.

If you've got a section of saran wrap in your pack, you could theoretically dig a hole and spread the clear wrap to make something of a solar still? One piece on the bottom to catch and one piece across the mouth.

Dew is tempting but it might actually require more effort than would be gained for the work.

Suggestions?

[Dick]

If the plants are transpiring (growing) you can secure a plastic bag over the green foliage and the transpired water will collect in the bag. I’ve never done it, but from what I have read / seen you would want several.

Definately look for depressions, and it is helpful to know which plant species are associated with a high water table...then start digging.

Haven’t done the dew think either but, in principle it should be really easy. All you are doing is walking around collecting food or firewood and occasionally wringing out the cloth you put on your ankles.

Keep in mind that you should be boiling the water. Maybe not so important if you dug a hole for ground water, but better to be safe than sorry.

[kevin]

If its a woods/hilly region as you described there will be watersheds collecting stormwater runoff; follow the drainages to point where it has concentrated in brooks - that's my approach

[Celticwarrior]

Look for bees. They can't live more than a few hundred yards (no more than a third of a mile) from a good reliable source of water, of some sort.

Also, check your foliage. Deeper greens can mean higher water content, generally. If you look at your lawn, you can tell where the water and sewer/septic lines are, or where there is an underground water run, because the grass grows thicker and greener there. The elements and minerals that the plants use are water soluable, and the higher amount of water subsurface is dissolving the elements and minerals and making them easier for the grass roots to take up. Nitrogen, various sulfur compounds, calcium, and a variety of other nutrients give the plants a stronger, healthier look with good deep chlorophyll. Water makes that absorption possible.

[Mephistopheles]

I alway keep an eye out for the Chevron sign or a Perkos...they both offer free water....

Actually, I've found cliffs offer a very good chance of finding water leaching out or caught at the base of same, especially dried streams at the base of waterfalls. If it is leaching out of the face then nearly 100% of the time it is cleaner than the water out of your home tap....if it's at the base it will almost always look like a septic tank overflowing and smell about the same...boil and charcoal strain it. I just use my MIOX and strain through sand and hold my nose.

Distilling water from the ground or vegatation is fine if you're just laying there in the shade waiting for rescue or want to "wet your whistle"....if you have to exert yourself to hike out and it is hot then you are likely good as dead as 2-3 days without water or low amts of water and you will be seeing martians, grandma or bigfoot in a bikini...at least in your mind...or bears like I have.

Animals and insects need water..follow well worn animal trails and they usually offer paths of least resistance and snakes. Insects on the other hand can survive on just dew...people can't really. Alot of desert animals live on dew in certain regions. I've tried the bird thingy but since birds fly 5 miles in nothing flat I gave up.

In hot or desert climates and terrain....figure about 1-1.25ltr hr for moderate-heavy exertion.

My desert pack loadout is: backpack=9.5#s, stuff=5#s, food=12#s and water=54#'s (24ltrs) for 3-5 days hard travel....get home dehydrated every trip.

If you have to travel...do it at night if at all possible....if you're going to hike in the desert its best to plan starting out when coming into full moon period to be safe.