Ok, the results are in!!! <img src="/images/graemlins/laugh.gif" alt="" />

Tonight I decided to put our little debate to the test, and see what in fact we would do to a lexan water bottle by dropping hot stones into it.

I used one of my old Eddie Bauer 1 L specials that I got at Target a few years ago. It's "leak proof cap" isn't very leak proof, so I don't use it anymore, and I figured it would make an excellent test subject.

I added 600 ml of water to allow for displacement. Then I started a fire (which is hot work when it's 99 degrees outside). Whew!

Initially, I decided to try using lava rocks, because I have them in abundance as we use them for mulch in some of our flower beds. I knew that they held heat well, and wouldn't explode on me. Good choice, right? Well....

Once I had some good coals started, I added the rocks then added some more wood to the fire. I probably let them sit 5 to 10 minutes. I have no idea how hot they were of course, as you wouldn't out in the field. I rolled them out of the fire with a stick, and lifted them using a forked stick (this worked even better than I initially thought it would). I should probably mention that the rocks were generally around 2" or so diameter. Basically just about as big as the wide mouth bottle would allow. Initially I added the rocks one at a time and checked for "boiling". Remember that with this method you won't see a traditionally roiling boil off the bottom of the container as you get with a stove. It will boil off of the rocks once it gets hot enough.

So I kept adding one rock at a time. It does require several rocks. Then I realized something. The lava rocks weren't really displacing the water and I was running out of space. DOH!!!

Note that the container was quite hot to the touch. I also wasn't initially replacing the lid between rocks, and I was losing some heat to steam. I dumped the water and rocks and started over, this time using rocks from my driveway (typical white driveway gravel), again looking for 1 to 2 inch diameter rocks that would fit through the bottle.

Same amount of water. This time I replaced the cap after each rock while I scooped up another one. Again, I heated them for 5 to 10 minutes. This time though, these rocks displaced the water, and I didn't experience the same problem. These rocks seemed to hold more heat as well (as would be expected).

The result was that I did manage to boil the water after adding several (10? I forgot to count them). By the last ones there was a roiling, lasting boil around each rock. Total displacement was approximately 200 ml or so.

I was so excited that it had worked, I proceded to do something very stupid. I tilted the bottle to see if there had been any damage to the bottom, and in the process managed to pour boiling water all over my fingers (remember the lid leaks, duh!). I now have a lovely burn on my ring and middle fingers. Note: do not get some impressed with yourself in a survival situation that when something works you immediately do something stupid that could be catastrophic!

Ok, so after I soaked my hand in cold water and applied some aloe gel, I head back out to check status. Water isn't boiling, but continues to steam quite well. Container quite hot to the touch. I dumped it all out and check the bottle for damage. There is no visible damage to the bottle. I refilled the bottle, and there are no leaks. The seam looks unchanged as well.

So in conclusion...

1. If you absolutely need to, you can boil water in a Lexan water bottle, by adding hot rocks to the water (DON'T PUT THE BOTTLE IN CONTACT WITH FLAME).

2. Your results will depend on the type of rock you choose. Remember that those round smooth river rocks may explode on you when heating.

3. Dropping rocks from a fire into water will get your water full of dirt and ash. You will probably want to filter it with at least a handkerchief before drinking.

4. The container transfers heat pretty well and will get quite hot. I also recommend using the lid to reduce heat loss between rocks, but be careful with pressure buildup (don't seal the lid tight!)

5. You won't be able to boil much water at a time due to the displacement. If the water level is getting too close to the opening you will get splashed when you drop rocks in.

6. Don't do something extremely stupid because you weren't thinking. Don't get in a hurry when in a critical situation. You will pay for it. <img src="/images/graemlins/crazy.gif" alt="" />

So now you know. It isn't terribly efficient, I still wouldn't recommend it, but in a pinch, this knowledge might come in handy. I did get probably 550 ml of boiled water in under 30 minutes (counting fire building), and could probably add another 550 ml in another 15 to 20 minutes (assuming another container).

Good luck! That was fun (except for the burned fingers part). More than one lesson learned!

Greg