Light a Fire With Water




Introduction: Light a Fire With Water

Dad, Maker, biker, trekker, I like sciences, technology, martial art and wild.

Hi everybody! In this instructables I will show you how to make fire with... water!

The principle is to use water as a refracting lens. It is not complicated, with a little training, we start a fire in 1 minute chrono!

To start a fire you need 3 elements: an oxidizer, a fuel and an activation energy.
The oxidizer will be the oxygen contained in the air, the fuel will be the tinder and our activation energy: the sunlight that we will concentrate in one point thanks to water.

Let's go!!!

Step 1: Components and Tools Needed


- Water

- A transparent plastic bag

- tinder (in this instructable I used sawdust and crushed coal)


no tools!

Step 2: Preparing Tinder

One of the most important things when one wants to ignite a fire is the tinder. That's 50% of the work.

For this instructable, I used sawdust and crushed coal.

- saw wood and recover the sawdust.

- crush coal.

- mixing

- put in a nest of dry grass, or in a bark for example.

Step 3: Preparing Water

We will now prepare our refracting lens made of water.

- put the water in the bag.

- Forming a carrot by twisting 3 of the corners of the bag.

- Tighten the bag to have an almost sphere holding it at point A and B.

Step 4: Light the Fire!

Now that everything is ready, we can light the fire.

- hold your sphere of water above your tinder and move it gently in order to obtain a concentration of light in 1 point as bright as possible, almost white.

- When smoke starts to appear do not stop! Continue until there is a lot of smoke.

- blow gently on your ember.

- Add wood more bigger and bigger

Now you know how to light a fire with water! congratulations!

Step 5: Bonus: All Steps and Demonstration in Video!

If you liked this project, subscribe to my Youtube channel !

Explore Science Contest 2017

Runner Up in the
Explore Science Contest 2017



    • Creative Misuse Contest

      Creative Misuse Contest
    • Water Contest

      Water Contest
    • Metalworking Contest

      Metalworking Contest

    27 Discussions

    Now I know what to take with me when I compete in Naked and Afraid! A transparent plastic bag!

    1 reply

    The author of the instructable is French, Fresnel was French . . .

    1 reply

    Yes I am French, but there are no links, promised! I did an abuse of language. And I misinterpreted explanations on a wikipedia page. Mea culpa!

    Pretty cool. chances are that if you need to start a fire in the wilderness and don't have other igniters or cannot get the timing down with shoestring + "bow" + twig + leaf + bark, you'll possibly have access to water and some trash you can use to focus the light through the water...

    kudos for the video and simple instructions. the image/diagram you shared in a response to house to hold the bag below was very helpful. It might help other visual learners grasp how you hold the bag to form a lens. I know it helped me visualize the elliptical shape necessary to focus the sunlight.

    Thanks for sharing! You got my vote because it's a simple and useful trick that not only applies basic light physics but also could very well mean the difference between a life and death situation after "acts of God" or car accidents, etc.

    Thanks again!

    1 reply

    Wow! Thank you very much for this comment! And for your vote!

    I think that it is a technique to master, among others, in order to be able to face an unexpected event.

    I'll add the shema to the Instructable, you're right this will be clearer.

    If this instructable can help someone in a critical situation, even just once, it will be the best reward possible (but I do not wish anybody)

    thanks again!

    BRAVO, Very Cool! I live where there is plenty of sunlight (Florida) and can hardly wait to try this! BTW, where did you get this idea? Or did you come up with it yourself?

    1 reply

    Thanks! I had this idea by watching Mythbuster and Series as dual survival ... And when I go hiking I always find plastic bags abandoned in wild. That's it that's all!

    Ah si seulement l'homosapiens avait découvert, avant le feu, le plastique ! En tout cas bravo, moi qui suis au soleil sous les tropiques, je vais tenter d'améliorer le système avec l'alcool de canne à sucre et la bagasse... Ca va chauffer. Félicitations pour cette idée et pour la vidéo.

    1 reply

    Merci! l'homosapiens perdu a aujourd'hui malheureusement plus de chance de découvrir du plastique que du feu... Production de rhum? biocarburant?

    Great instructable, except that is not a fresnel lens. It's a standard refracting lens. Fresnel is made by layering transparent flat sheets of glass, plastic, etc. to focus the light.

    3 replies

    In the absence of "coal dust", I would bet that a bit of char-cloth would work.

    Good Instructable!

    1 reply

    Thanks! Yes I think it will work without problem. Even sawdust alone works, it's just a little longer.

    How do you hold the plastic bag with water to concentrate the light? Do you point the pointed corner of the bag towards the tender or do you point the pointed end towards the sun? I'm sure it wouldn't be that difficult to figure out but some clarification would help, thanks...

    1 reply

    I will try to explain with a quick shema.

    - To form the almost sphere, you hold the angle 1 2 and 3 together and you make turns.

    - Then you hold the bag in A and B, so the bag is horizontal.

    - When you get to concentrate the light, you must avoid moving too much ...

    I will do it again in a bivouac in less than 15 days (if there is sun!), I will have to have a second camera to shoot under 2 different angles, and I will post it on youtube.

    Sans titre 3.jpg