Here's the deal. I'm planning a camping trip with my daughter that will take us to the top of a high ridge for two nights. The ridge has no water at the top but there are several seeps visible with binoculars from an opposite hill where we usually camp.

We will be doing this trip in July, dry/cold season for Brazil so I don't want to depend on these seeps to replenish our water supply. The ridge is always covered in cloud in the morning and I'm betting there is a healthy dew on the ground up there.

I know we could soak up water with sponges but is there a more effective way to harvest water from heavy fog? I know our tent will get covered with hevy dew and will probably yeild a half liter in iteslf. I would like to pack in a days supply of water and harvest enough to stay another day if possible. Mac

You could try a space blanket or a big sheet of plastic. That doesn´t have to much impact on the taste of the water. I recommend taking a supply for both days anyway. That way you don´t risk anything if the harvest is disapointing.

A quick google turned up this reference to fog harvesting in chile. Seems to me that a simple expedient form of this approach could be constructed with some mosquito netting and a couple of hiking staffs or found limbs from nearby trees.
Since you want to be walking in you need to be light in this answer. I would think that you could carry enough mosquito netting to form a decent double layer triangle with the point downard such that your collector would funnel dropplets into a resqvoir at the point of the triangle. With some cordage you could hang this from nearby vegetation or other liberated limbs if there are no trees on the ridge.

Let us all know what works!

So this ridge got leafy trees or bushes on it?

If so, I'd think all you need is a good sized plastic tarp to harvest all the water you want.

Benman,

The ridge is real high. There's no actual "treeline" here due to altitude but there's not enough water up there to support trees, or leafy bushes for that matter. It's sort of like the Moon with grass and scrubby little plants in places. The view is incredible. The ridge is also topped with large rocks and boulders, a very rugged, craggy place.

Down off the crest there are several places where water seeps out and is visible with binocluars. I'm going to scout it out better before we plan to spend the night up there.

Every morning there is a thick bank of cloud spilling over the ridge into the valley. I'm just betting it's wet enough up there at dawn/early morning to harvest enough water to spend another day.

I'm trying to avoid two things, climbing down to a seep and packing in another five liters. Mac
Mac

OK, no trees/shrubs but you've got wind.

I would try setting up a plastic tarp that is at a 45 degree angle to the wind. I would also put, lets say a 10-15 degree v-shape into the middle with the crux at the bottom. A couple of small rocks should help with that. I would then put a pan underneath the lowest point on the tarp. Get it? You're in effect modeling a seep like on the ridge.

I think it will work but you may have to do some tweaking with the angles to maximize your flow.