I have been trying to find a clear plastic sheeting that is actually transparent, not merely translucent like the standard hardware store carries; also their truly clear stormdoor plastic is not wide enough. I need a 10' x 10' piece. Does anyone know of where I can get this?

Polyethylene is naturally a bit cloudy, as far as I know.

Clear vinyl might be the solution. I've bought large, wide chunks from Home Depot by the foot. It's very tough, great for emergency windows that you can actually see through.

10' wide might be harder to find though. As Izzy suggests, a plastic specialist is probably the place to look.

The downside is that vinyl is a toxic environmental pig through its whole life cycle. A shame, because it works so well. So it goes.

Depending on how thick you need it, I've gotten from Walmart the winter window sealing kit that has pretty much transparent plastic. It's pretty thin, but tougher than you might think. You'd have to double check the size but it would come out pretty damn close to 10x10 (I've got big windows).

Thanks for your suggestions, but I'll just go with the standard translucent sheeting. It's not perfect, but it should be transparent enough.
By the way...it's in case I need a solar still (main purpose), but can also serve as tarp.
I know, I know, they don't work. But they do if you know when and where they are applicable.
I'm making a canteen kit and I'm attaching everything applicable to water I can think of.

I have a Maxpedition canteen pouch (I removed the Velcro and replaced with fastex buckles and straps), a bottle of Polar Pure, some chlorine dioxide tablets, trioxane, 1 quart GI canteen, GI cup, GI stove, Millbank bag (I scored a new one cheap from UK!), some paracord to suspend bag, a large bandanna, a length of aquarium tubing, twist ties to hold tubing to a stick, a sealable liter water bag, and heavy duty foil, spoon, and P-51. I'll add a new lighter and the sheeting soon. That little pouch holds alot.

Maybe I'll post pics later.

Did I overlook anything?

Just a passing thought on the solar still...

I know that they don't work in the desert very well. If there's no water near the surface, there's no water, period.

But in a place like the PNW, they might work okay. Just because there's no actual water source wouldn't necessarily mean there's no water.

Sue

Does the PNW mean the post-nuclear world? I can only guess how that'd be.
But I imagine they work just fine if filled with vegetation and even urine; or where there is only unpalatable water like on a beach or salt marsh.
The only problem I am having with the plastic is that at 7' x 7' it doesn't fold up small enough to fit on my canteen kit. So I'll either rig a way or it wil be somewhere else.