Can You Microwave Hot Water Bottles
What to know

Can You Microwave Hot Water Bottles?

The microwave heating silicone or rubber hot water bottle bag requires hot water in order to work. It’s a topical way to relieve muscle, joint, or wound pain. Just apply to the area. With that said, can you microwave the water inside hot water bottles?

The makers of the microwave heating bag or hot water bag typically make it with silicone or rubber. It’s used for hot and cold therapies for back pain, muscle pain, joint pain, arthritis, and more. It may or may not come with a knit cover. Anyone can use it. Just add hot water, like with instant noodles.

The heat from the hot water or perhaps coldness from cold water permeates from the bag to the injured area.

Can You Microwave Hot Water Bottles?

Most makers of hot water bottles use rubber and other microwave-unsafe materials with no FDA approval for safety. For all you know, the rubber hot water bottle you’re using might burst into flames while inside the microwave oven.

When we tried microwaving a hot bottle while covered in its knit cover, it ended up inflating and smelling of burnt rubber. It might seem like the path of least resistance involves simply putting boiling water inside the water bottle as intended.

Hot Water Bottles
Hot Water Bottles

The Release of Toxic Chemicals

Microwaving a regular rubber hot water bottle or cushion can release harmful toxins like BPA. Yes, you won’t be consuming the water inside the bottle but the toxic smell could permeate unto you while using the bottle itself.

Some toxins prove to be carcinogenic (cancer-causing) as well, or at least has links to increasing your chances of getting cancer.

Look for the Microwave-Safe Label

Like with food containers, your hot water bottle shouldn’t be microwaved without a microwave-safe label on it as a rule of thumb. You cannot microwave plastics, rubbers, or rubber-like compounds without that label.

The much safer way to “microwave” a hot water bottle? Microwave the water you’ll use for it till it boils then transfer the water to the bottle after the fact. Regular hot water bottles might inflate then blow up, taking your microwave oven with it

How to Microwave the Microwave-Safe Hot Water Bottle

You significantly reduce the chance for destruction by microwaving only microwave-safe hot water bottles. Even then, you need to follow instructions on how to microwave it by its manual or through this guide. This is to avoid accidentally building up pressure inside the bottle.

Don’t heat up the water inside the hot water bottle at high temperatures. Instead, put your microwave at medium power and heat up for 2 minutes. Quickly retrieve it after heating as well.

Premium Classic Rubber Hot Water Bottle
Premium Classic Rubber Hot Water Bottle

What Happens If You Microwave a Hot Water Bottle?

Many wish to heat their hot water bottle directly with the microwave instead of making hot water to put on the hot water bottle. They might feel it’s a hassle to boil water or waste fresh hot water used for instant coffee and noodles.

However, it’s actually more of a hassle to do things this way. Don’t heat up the water inside the hot water bottle. You could melt the bottle or make it contaminated with BPA. If you microwave the hot water bottle, it could release chemicals, melt, or explode.

Most of these bottles don’t have microwave-safe labels. When you heat them up, the rubber materials could burn or end up aflame. You also risk releasing carcinogens on top of plasticizers and volatile organic compounds (VOCs).

How Do You Know If a Hot Water Bottle is Microwave Safe?

When purchasing hot water bottles, you should try to see which ones have a microwave-safe label or not. Most don’t. Most feature rubber bodies that react negatively against microwave radiation. Better to boil water with the microwave then put it in the bottle than to microwave the bottle.

As for plastic water bottles, you shouldn’t microwave them. You should also follow the put boiling water on the bottle if you were to use it as a makeshift hot therapy bottle.

These PET (polyethylene terephthalate) bottles do have recycling identification numbers below to indicate if they’re BPA-free.

You may also like: What are The Best Microwavable Heating Pads?

How to Tell If Plastic is BPA free?

As for water bottles made of plastic, here’s the deal.  Make sure your water bottle offers BPA-free features and microwave-safe features. You can use these easy-to-do tricks that you can apply in order to check the microwave safeness of your water bottle.

  • Reverse the Bottle: Check the resin identification code below the bottle. It’s the recycling code you need to look for—the one with a triangle icon. You can see any number from 1-7 there as well.
  • Numbers 1 2, 4, 5 and 6: If you notice any number of 1, 2, 4, 5, and 6 or not 3 and 7, this means the hot water bottle is (relatively) safe to microwave and BPA-free. The #5 plastics specifically feature complete microwave-safeness.
  • Number 3: If the bottle gets 3 instead, it means it’s made of PVC. This contains BPA. Most plastic water bottles for beverage use don’t use #3 code plastics. PVC usually get used for pipes and industrial items.
  • Number 7: It might or might not contain BPA if it’s Code 7. Though you can find this plastic in many fields, you can’t be sure they’re completely harmful when mcirowaved. It’s a toss-up versus going for a #5 one.

Then again, as a rule of thumb, don’t microwave water bottles. The only plastic items you should microwave? Plastic containers with microwave-safe labels like those from Rubbermaid and Tupperware.

They’ve been manufactured with microwaving in mind. PVC plastics shouldn’t be used to house beverages due to their high BPA content. Some plastics could also leach off BPA when microwaved due to BPA’s importance in plastic manufacturing regardless.

Also, Take Note

Can you microwave your hot water bottle or not? No, you can’t. If you can—if you’ve found a hot water bottle with the microwave-safe label—then follow the instructions on it or its instruction manual in regards to microwaving it safely.

You need an FDA-approved, BPA-free hot water bottle with the microwave-safe label on it. On top of that, you should heat it for 2 minutes in 1-minute increments at a medium power level to prevent pressure build-up.

In short, even if you could microwave a hot water bottle, it’s much simpler to just put hot or boiling water inside of it.


  1. Is It possible to re-heat a hot -water bottle in the microwave?“,, February 1, 2007
  2. Can You Microwave a Hot Water Bottle? Is It Better“,, Retrieved November 17, 2021


Through the years, the microwave oven has become a standard appliance for all homes. It is safe to say that there is no home without a microwave oven. If you are looking for a microwave oven that best fits your needs, You find the right website.

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