MRE Heater Not Working: 4 Possible Reasons and Solutions

Imagine being on an adventure and you’re hungry as hell. So you unpack your MRE, put some water in the heater and wait for 10-15 minutes. But then you find out that your meal is not warm enough. So frustrating right?

So, why is your MRE heater not working?

There could be several reasons that could hamper your MRE heater. Some reasons are a punctured pack, too much water, poor or expired MRE. Unfortunately, you can’t reuse an MRE heater. But you can look out for the below-mentioned factors to avoid your MRE heater not working.

Not sure about the details about the cause of your MRE heater not heating up? Don’t worry yet. Here we’ve explained everything that could cause this problem and how to avoid them in the future.

Why Is The MRE Heater Not Working?

There could be several culprits to blame if your MRE heater isn’t heating up properly. Some of the usual suspects are-

These are the main reasons for which MRE heaters don’t work.

But no need to sweat yourself yet! Problems only exist so that they can be solved, right? So, get on board with us and see why your MRE heaters are not working! And we’ll solve each of the problems as we go.

Reason 1: Punctured Pack

The first and foremost trouble is a hole in the heater pack.

The MRE packs that we usually use are water-based. We simply put our meal and the heater pack in a container and put some water. Then the heater pack generates heat itself and makes your meal ready to eat.

But if there is a hole in the heater pack, the generated heat starts to leak through the puncture hole.

If the heater bag that you’re using is punctured, the heat gets diffused to the outside environment. As a result, the meal doesn’t get enough heat inside to be ready.


Now, let’s see how to fix a punctured pack?

You could solve this problem in two different ways. The first one is, you can change the heater pack. Then get one that doesn’t have any holes. But if you don’t wanna waste the heater bag, there is another way. Check from where the heat is leaking from and put some tape on the leak.

However, if the hole is too big to cover with tape, then use a new heater.

The heaters we usually use can heat up to 40°C. And some of the heaters can reach even 93°C. So you need a tape that can hold out against this temperature. You can check out these top-notch tapes and get one right away-

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Both of these tapes can withstand more than 200°C. Not to mention, you can always use these tapes whenever and wherever necessary.

However, this works only if the puncture was created an hour or two before using the heater. If the puncture was created a long time ago, this method won’t work.

To understand this, we need to know how MRE heaters work. Simply, when the magnesium of the heater comes in contact with water, the metal starts to corrode. This corrosion is what generates the heat.

But this doesn’t happen with a long-living hole. Because of the hole, the inside of the pack is exposed to the humidity outside. And as we saw before, the humidity is what corrodes the metal.

Through the small puncture, the humidity in the air finds its way inside the heater bag. As a result, they start corroding the heater elements. But the metal corrodes on such a small scale that we don’t even understand when it happened.

In this case, we’re afraid you have to let this heater bag go.

Reason 2: Too Much or Too Less Water

Another significant issue is putting too much water in the heater bag.

The heater bags are made in a way that they’ll heat up with a certain amount of water. If you put too much water, it won’t heat up properly. This also happens if you put in too little water.

Because if you put too little water, the heating elements won’t get enough water to heat up. Also, don’t put in too much water. Else, the heater bag could burst due to excess pressure.


So this question naturally arises, “How much water should I put in MRE?”

In every MRE heater pack, there is a label that says to fill up water to that level. Now, this level varies from brand to brand. But the label sure is in every pack. All you have to do is fill water up to that level. And then wait for 10-15 minutes until your meal is ready.

Sadly, MRE heater bags can be used only once. So if you have already poured in too much water, you need to use a new one.

Source: Wikipedia

But what if you added less water? Can you fill it up to the required level later and get it heated up?

Unfortunately, no. If you already poured less water initially, that water has already generated the heat it could. Later if you add more water, it won’t add any more heat. Because the previous amount of water has already used up all the elements.

Either way, you need a new heater bag. But you can always be cautious for the future!

Reason 3: Poor Manufacturing Quality

Sometimes, we have to pay for others’ mistakes, huh?

This is exactly what happens when the heaters come faulty from the manufacturer. MRE heaters use magnesium as metal, a little iron as alloy, and salt. It’s not impossible that when manufacturing, a pack or two will turn out to be faulty.

All of this could happen because of compromised quality control. In this case, it’s nothing but pure bad luck.


Unfortunately, we can’t do anything about faulty MRE heater packs. But you can also carry some extra heater bags along with MRE bags. Because, if your meal comes with a heater bag already, and it’s wasted, you’ll need another one.

You can check out these heater bags to carry along.

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Now that you have these additional heaters, you don’t have to worry about running short.

Reason 4: Expired Heaters

Wait a minute, do MRE heaters expire?

Everything has an expiration date and MRE heaters are not any different. MRE heaters usually last about 5 years in intact packs if kept in 75°F or below. After the shelf life exceeds, the heater won’t function properly.

Some of the packs can last even 3 or 4 years. As a result, even if it’s sealed and water poured the right amount, it won’t heat up properly.

Because the elements of the heater lose their efficiency over time. Sadly, there isn’t anything that can be done about it.

So these are the four reasons your MRE heater might not be working. Hope we could help you save your trip.


When it comes to heater bags, we can’t just solve the problem and use them again. So what is even the point of all these talks, you might be thinking.

Well, prevention is always better than cure and we all know it. We’re discussing all these so you can avoid these problems in the future.

You can follow these instructions for time to come and be prepared-

Put in The Food Pack Carefully

When packing for an adventure, load your food and the heaters carefully. It’s easy to damage the heater while trying to put the food inside.

Keep the heater away from any sharp object to avoid unwanted punctures. So, if you have an assault pack attached to a rucksack, then we suggest you keep it inside the rucksack.

Don’t Keep The Heaters in a Wet Environment

From the discussion till now, we’ve learned that MRE heaters are highly reactive to humidity. So try to keep the heaters away from water. The best would be if you can keep them in a different container.

This way the heaters won’t get exposed to ambient temperature.

Follow The Instructions on The Heater Pack Properly

Every heater pack comes with instructions on its body. Follow those instructions very carefully to get the proper outcome.


Question: Can you eat expired MREs?

MREs don’t have any particular expiry date. You can eat them even after four or five years. But it’s better not to consume MREs that have been stored for more than three years.

Question: What does MRE mean?

MRE stands for Meal-Ready to-Eat. MREs include a main dish, side dish, desserts, etc.

Question: Can anyone buy MREs?

Absolutely! You may have seen that military personnel frequently use MREs. It’s because MREs are very convenient at any place. This is why the confusion arises regarding MREs. But anyone can buy MREs. 


When going on hiking or trekking, MREs are the best possible solution to calm your hunger. And therefore, you need to be careful about packaging them.

As we’re here, we hope you’ve got your answers to why your MRE heater is not working.

We don’t want you to face this issue ever again. So, see you never!