Boiling Water


Let’s Talk Boiling Water:

A popular topic within the world of outdoors, not just hiking, is whether or not to boil water, and if so for how long.

Most long distance hikers, and those of us who are sub 2268 hikes, that I know do not bring our water to a full boil.

While exact temperatures means next to little out on the trail, after all, who the hell takes a water/liquid thermometer with them while hiking, it is important to at least understand the basics, such as how elevations can affect water temperatures, and thus how long it will take water to reach a higher temperature.


Realistic Water Temps For Hikers:

I tend to feel that the C71° – C82° (F160° – F180°) is the ideal temperature range needed for your food rehydration, and coffee/tea, when out on the trail.

It is, absolutely, important to understand that I share this with the understand that my water has already been filtered or purified (do your homework on the differences between those two important words!) such as with a Sawyer Mini water filter or Sawyer Squeeze water filter, or for those serious adventures the MSR Guardian water purifier. In those very rare situation where you need to boil for water filtration/purification purposes, obviously allowing the water to reach a ‘hard/full/rolling boil‘ is imperative.

I read somewhere a few years back that the last 25-30 degrees that it takes for water to go from “hot enough” to “hard/full boil” results in an additional 20% of fuel being used.

For long distance hikers that results in a significant amount of weight over the course of the hiking season, all for something that is just not necessary – except for that very rare situation where you might need to boil for filtration/purification purposes.


Fun Classifications Of Water Temperatures:

Over the years there have been a few different methods that folks have used to term, or describe, different water temperatures, and here are two of my favorite methods:


Shrimp Eyes
about 70-80 °C (155–175 °F) – separate bubbles, rising to top

Crab Eyes
about 80 °C (175 °F) – streams of bubbles

Fish Eyes
about 80-90 °C (175–195 °F) – larger bubbles

Rope of Pearls
about 90-95 °C (195–205 °F) – steady streams of large bubbles

Raging Torrent
rolling boil, swirling and roiling


Tepid Water
85 to 105°F. The water is comparable to the temperature of the human body.

Warm Water
115 to 120°F. The water is touchable but not hot.

Hot Water
130 to 135°F. The water is too hot to touch without injury.

160 to 180°F. The water is beginning to move, to shiver.

185 to 200°F. There is movement, and little bubbles appear in the water.

Slow boil
205°F. There is more movement and noticeably larger bubbles.

Real boil

212°F. The water is rolling, vigorously bubbling, and steaming.


Again, it is important to remember that if you have water that has not been filtered/purified, bringing the water to a full/rolling boiling is the safest thing you can do.

If you have the means, and legal permission within your area to do so, using wood stoves/fires to boil large quantities of water is ideal, saving you fuel that you have to carry in.

But, if you have the means to filter/purify your water, there is very little, to absolutely no need to waste your carried-in-fuel bringing your water to a full/rolling boil.

5 thoughts on “Boiling Water

  1. Agreed.. Nowadays a little trick I use when I need to filter my water first is to run it through a Sawyer mini first then bring the water to near boil. But never full rolling boil. A great way to save lots of fuel over the course of a thru hike.

    1. I do the exact same thing… run it through my Sawyer mini, then heat it up to around the Shrimp Eyes to Crab Eyes point (awesome terms btw), or right to the point where it looks like it’s getting ready to boil. I’ve been amazed at how much of a fuel savings I’ve realized from making this change, and no problems with undercooked meals.

  2. Thanks always John for your efforts to make things more fun and interesting. This year we used the Windburner for 8 weeks of hiking in japan. I brought along a pocket rocket as well . The Windburner is a bit heavier (430gms) but uses 10% less fuel so the weight savings on fuel carry may make up for the difference. It comes down to whether there will be wind. Wind can double or more the fuel per burn. For Scotland again next year I will bring the Windburner as it is often rainy and windy and remote so fuel has to be carried. Anything that minimizes fuel consumption saves weight carry and anything that reduces wind effect reduces fuel carry weight as well. I have used alcohol but given the downsides and the recent reports of experienced people burning themselves I will opt for canisters instead from now on. I would hate to spill alcohol when cooking in the vestibule of my Zpacks Duo as it would likely be a major issue. I will begin measuring the burns used each time and see if I can put figures to the weight effect. For volume the Windburner is superb as it nests everything for kitchen well. I think it will be around 10gms per burn but in wind the Pocket Rocket would be 20 Gms. If I assume 2 burns per day that is 5 days per canister vs 2.5 days with PR. It would mean carrying an extra canister at 250 gms.
    Any thoughts on the comparison?
    Thanks again.

  3. Bring water to body temp before using it, to make the most of your fuel- Regardless of stove.
    I made note of this on my 2016 August trip on the Allagash river where we camped right next to a natural spring…the water took much longer to boil because it was refreshingly cold. We had the BRS 25g stove along with the Optimus Terra weekend HE main pot only.

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