Boiling water in PET bottles - Does that really work?

👉 The key facts from this guide

The headline sounds totally crazy at first, right?

When I read this in several survival books, I could hardly believe it.

I just had to try it myself – and it actually works!

The water tasted completely normal, without any plastic taste at all.

This is how the emergency method works

The reason it works at all: PET melts only at about 260 °C, while water boils at 100 °C. This gives us a safe temperature window.

The steps:

1. Fill the bottle to about 80% (the bottle shrinks when heated)
2. Place the bottle without a cap about 12–15 cm above the embers – it can also be placed in the embers
3. Wait for bubbles to rise (this may take some time)
4. Continue heating for about 1–2 minutes
5. Let it cool down

Here is the appropriate short video for that (in German):

Risks and Considerations in an Emergency

I can already imagine what your concerns about the method might be:

Doesn't microplastic get into the water?

Yes, indeed that can happen (but I did not have the water tested). Nevertheless, I would like to clearly list the advantages and disadvantages of the method here:

The problem with untreated water:

• Severe diarrhea and vomiting
• Extreme fluid loss
• Quickly life-threatening in the wild
• Critical without medical assistance

The PET method:

• Yes, some plastic could leach into the water
• One-time consumption is less dangerous than contaminated water
• Only suitable for real emergencies

The fact is: The risk of some microplastics is lower than dying from contaminated water.

The same bottle should not be reused multiple times, as more chemicals may be released with each heating. Thinner bottles also work, but thicker ones last longer.

Comparison of Water Treatment Methods

I would like to give you a brief overview of the water treatment methods. This way, you can see which methods are ideal and what they are useful for:

Method	Removes bacteria	Removes viruses	Removes heavy metals	Removes chemicals	Special features
Boiling	Yes	Yes	No	No	Energy-intensive, but very safe
Homemade filter	No	No	No	No	Depends on filter quality
Water filter (industrially manufactured)	depending on product	depending on product	No	No	Depending on pore size, may also remove viruses or bacteria
Distillation	Yes	Yes	Yes	Mostly	Very complex, but the safest
UV light	Yes	Yes	No	No	Requires clear water and takes a long time

Boiling (Water Disinfection) vs. Filtering (Water Purification)

Boiling:

• Reliably kills all pathogens
• Works even in very cloudy water
• Only needs heat and a heat-resistant container
• Does not remove heavy metals or chemicals

Filter:

• Filters suspended solids and larger particles
• Some filters also remove heavy metals
• Viruses are often too small for normal filters
• Filters can clog or fail

Last Words on Emergency

It is clear: The PET bottle method is not ideal. But when you are outside, your water is all gone, and you only have a plastic bottle – then boiled water is definitely better than contaminated water to drink.

For the future: Plan your tours well. Bring enough water. But also know: Sometimes you find yourself in unforeseen situations. Then this knowledge is worth its weight in gold.

Here you will find more references to read up on:

• Finding, collecting, filtering, and making drinking water – the ultimate water guide
• Survival time without water: How long can the body last without fluids?
• The 11 best outdoor water filters 2025 for clean drinking water while camping
• Boiling water without a pot: These 8 methods will help you get drinkable water
• Can drinking saltwater or seawater make you sick or even kill you?

And if you want to test your knowledge, then check out the Water Survival Quiz.

What do you think – surprising that it really works?

PS: In my test, the water tasted completely normal, by the way. No plastic taste, no change – just completely normal boiled water.

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