When climbing, weight is always an issue. One should travel light enough to be efficient, but have enough gear to safely complete the task. The more time spent climbing and the more experience one accrues, the more little tricks and methods are developed to lighten the load. One of these is instead of carrying water, which is inherently heavy in comparison to most gear, is to carry only what they need for their climb. While resting for a night or extended amount of time, melt surrounding snow and ice for consumable water.
This sounds easy but can be difficult if never attempted. Start out with a small amount of water in the cooking pot. This will allow the heat to conduct better through the warm water into the surrounding snow. It will also eliminate scorching the pot which can taste like burned water when complete. Decide before hand if you want a hot drink, or just drinking water. If drinking water is all that is desirable, then simply melting the snow until its cool water is enough. Pour it in the water bottle and add chlorine dioxide tablets or drops like PUR or Aqua Mira. This will save fuel by eliminating the boiling process. If one wants a hot drink, it’s easiest just to wait for a boil before consuming the hot water. It will be safely sterilized from pathogenic organisms after reaching its boiling point.
White gas stove components with stove base and mini lighter, windscreen and pot
The stove set up should use a ground reflector, and side reflectors to conduct heat better and block out wind. This saves on fuel as well. The stove should be on a high setting; flames barely lapping up the side of the pot will melt snow faster and be more effective rather than having it simmer at a lower heat. A well made pot with rounded edges made of aluminum and a lid that creates a good seal can make a big difference in boiling speed, spend the extra money on a nice pot set that will last longer and do the job more efficiently. If using aluminum, wind screens are a must or else the heat will be conducted away from the pot instead of toward it. Aluminum is a great heat conductor, so you want it working for you.
Stirring the snow and ice chucks will break them up allowing the heat to infiltrate more surface area of the chunks and melting it faster.
If boiling water in a vestibule, dig a hole in the snow to put the stove in. This will block it from more wind, and also prevent the stove from falling over as it would slowly melt its way down through the snow. One can also put the stove on a shovel to help with stability and reflecting heat back to the pot.
Small butane stove with Brunton remote stove base.
Butane and blended fuel s are stored in pressurized canisters in liquid form. The fuel must be able to vaporize to burn. At sea level butane vaporizes at about 30° F (-1 C), isobutane at about 15° F (-9 C), and propane at -43° F (-41 C). When using canister stoves in cold weather, place the fuel inside a parka or sleeping bag until ready to cook, this will keep it warm. As fuel leaves the canister, the canister cools. Warming the canister with your bare hands or dribbling warm water from the pot over the canister will improve cold weather performance. Stoves with a remote canister will allow the canister to be inverted to force liquid fuel to the hot burner head, instantly vaporizing it.
Priming a white gas stove. Don't do this inside a tent.
White gas is not available in all countries, and is also heavier than canister fuels. It is liquid at normal atmospheric pressures and temperatures, so it must be both pressurized and vaporized before it will burn. Stoves using white gas are manually pressurized with a pump. The stove must then be primed by allowing a small amount of the liquid gas to flow through its generator tube and into a small cup at the base of the stove. The gas is ignited which vaporizes the fuel in the generator tube. Fuel is then allowed to flow to the stove which vaporizes in the hot generator tube and then burns, putting out huge BTUs.
Each stove is different and made for different purposes, so before you go out and start melting snow, make sure the stove will get the job done, and not waste, or even use valuable fuel and time.
On a few occasions I have been forced to melt snow. The result has always been brown colored water. Even when I let the water settle overnight, the next day the water was still brown and I could feel the crunch of the dirt under my teeth. If you don't like that, you better have a filter.
I still rather collect running water whenever possible, even if it is just a trickle coming from a tiny snow patch.
1) Sterilizing water by boiling becomes less and less safe, the higher you go, at least in theory. As the boiling point of water is lower at high altitude, it will be less efficient at killing the bugs. If you are in a clean environment, this is not a problem, but in a busy camp area this is something to keep in mind.
2) I think I speak for many, when I promote adding the temperatures also in Celsius :)
I usually look at the snow to decide if it needs boiling. Is it pure white with no dirt or color other than white? It shouldn't need boiling or treating. Chlorine is not good for you and even Iodine kills your normal digestive bacteria and only in very rare cases are these things protecting you from anything. Of course this doesn't apply to a crowded camp area, or somewhere with a lot of animals.
You are correct, chlorine is not good for you, however, ingesting chlorine for short periods of time is less harmful than contracting a microbial illness. If you contract a microbial illness any antimicrobials you may end up taking will kill off beneficial flora more than water treated with chlorine. Chlorine can also be deactivated after the desired contact time using ascorbic acid (vitamin C). The one situation where chlorine is not recommended is water sources with high humic acid concentrations (think tea colored water). Chlorine combines with humic substances to form trihalomethanes, a carcinogen. This is not usually a problem in the alpine, but can be in low lying forests. While iodine is not my choice, it is effective against bacteria and virus particles which are far more prevalent than protozoans.