I assume you're going to boil the water by dumping hot rocks into this makeshift container?

If so, a word of advice: You'll need a LOT of rocks.

Water has a *ridiculously* high specific heat capacity, so whatever weight of water you wish to boil, you'll likely go through a number of times that weight in rocks.

Therefore you need to have a way to both put rocks into the water, and to take them out. Over and over and over and over again.

You could try making the rocks hotter, so each has more heat to give up to the water, but then you just get a lot of steam as the water in contact with the rock boils instantly, and all that "extra" heat escapes.

I think this whole scenario demonstrates just how friggin' important it is to have something, anything, that's capable of holding water.

While I can appreciate the experimental nature of this quiz, I think in that situation I would probably just make a natural water filter out of my sock with available grass, dirt and hope for the best.

About the only idea I've seen that seems worth an attempt is finding, digging a hole, building a fire, heating rocks to drop in, catching the steam with shirt and wringing out. Although firing the clay pot seems like an interesting idea...what would happen to me is that I would spend 6 hours working on a clay pot that wound up not holding water. <img src="/images/graemlins/tongue.gif" alt="" />

The way I understand it a properly fired earthenware pot (which is only fired to about 500*c) when done over an open fire) will go fine over an open flame for cooking, boiling, etc. This is not like ceramic coffee cups in the cubbord at home (fired at around 1000*c) which would in fact crack when in contact with any uneven heat like cooking or boiling over an open flame. This is based on what I read at BCUK... I have not test it yet. We'll know for sure soon enough. Hopefully I will find the time to try this experiment this Sunday but if I dont, I have a camping trip planned for May 30th through June 3rd and will certainly have the time to try this then.

Ok, so what's wrong with making a filter that uses the clay we have discussed and the only other thing we have...fire.

http://info.anu.edu.au/mac/Media/Media_Releases/_2005/_January/_190105filters.asp

Thanks to TWheless for the article...very neat concept, should be a wonderful find for third world countries. My only question would be, does it have to be terracota clay? or will any clay that can be heated work?

Think you could contruct that and get a liter of water trough it in eight hours? If you did, it still won't kill all possible nasties. There are not even any commercial non-chemical filters that do. That filter also requires coffee grounds and cow manure.

I know that viruses are smaller than bacteria, but are cryptosporum & giardia cyst larger or smaller than bacteria?

And can you imagine some dingbat dumb enough to carry coffee but nothing to heat it in???

Sue

Larger then bacteria.

Pete

For some reason that I have not figured out yet, many PHRASECENSOREDPOSTERSHOULDKNOWBETTER.-types don't consider boiling a viable means of water purification. I have talked to more than one person while strolling through the isles at REI or some place similar and I get the striking impression that if their pump action water filter clogged they would die of dehydration. These are people that for whatever reason, don't carry chamical purifiers as a backup and don't even consider boiling, nor do they carry any equipment with which to boil water even if they wanted to.

She followed the river downstream until she found a shack, because her father had once told her "If you follow the river downstream far enough, it will always lead to civilization." So yes, she did have plenty of drinking water available, if nothing else.

There's no question that she was extremely lucky, in many ways; but like many survivors, she made the most of it when it came her way. The others had the same luck, if not better; and they squandered it.

I'd probably try using clothes. Maybe make a fire, put a "dry" rock in the coals, and let it heat up. While I'm waiting, I'll try to make a container out of the sturdiest cloth I have on me, fill it up with water, and set it on the rock. I'd hope the rock would not burn the wet cloth, and would get the water up to temp. I don't know if it would work, but I'd have to try something.