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Can You Freeze a Hot Water Bottle?

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By Elizabeth Masterman

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When a heat wave hits, people will try anything to get a break from the unbearable heat. One recent craze saw people putting their hot water bottles in the freezer desperately trying to cool down! But will it work, and is it safe?

Can You Freeze a Hot Water Bottle?

Yes, you can freeze a hot water bottle. Fill it half full of water, squeeze the air out and secure the lid, then freeze it. Take it back out when frozen and use it to help you keep cool. Freezing a hot water bottle can damage the rubber seal, so keep that one for summer use and don’t use it for hot water.

How to Freeze a Hot Water Bottle Safely

Freezing your hot water bottle is simple. Just fill it with cold water rather than hot water.

As with hot water, ensure you only fill it half to two-thirds full. This will allow space for the water to expand as it freezes. Make sure the top is screwed in tightly, then place the hot water bottle in the freezer. Leave it in the freezer until frozen solid. 

You can then take it to bed with you, or place the frozen hot water bottle in your bed under the sheets to cool them down before you get in.

Hot Water Bottle to Cool Sheets

Alternatively, you could place one on your pillow, then when you get into bed you could pop it under your pillow, so that when you flip your pillow the other side will be cool.

If you are worried about getting the bed sheets damp, an alternative would be to place a frozen hot water bottle in front of a fan. This way the fan will push the cooler air above the frozen hot water bottle around the room, rather than just circulating warm air.

You could also keep the bottle against your skin for maximum effect. Placing your hands or feet on the frozen hot water bottle can be particularly effective.

If you’re going to do this, it’s a good idea to pop it in a hot water bottle cover or wrap it in a towel or tea towel. This will stop your skin from coming into direct contact with the ice-cold surface and will also act as an absorbent layer for any leaks or condensation.

Dangers of Freezing a Hot Water Bottle

Do be aware that if you freeze a hot water bottle, this is likely to damage the rubber seal around the lid, which could make it leak. If you then use it for its intended purpose again, hot water could leak out with a risk of scalding.

For this reason, it’s a good idea to have one hot water bottle for the summer months and a different one for the winter months.

Perhaps choose a red one for summer and a blue one for winter, or write S or W on each one using a permanent marker.

Also be aware that a bottle filled with ice is likely to build up condensation on the outside. This, coupled with the risk of leaks, could make for a soggy mattress if you take your frozen bottle to bed.

This is likely to be unpleasant in the first instance, but also could be dangerous as mattresses take a long time to dry and, if left untreated, could develop mould.

Avoid these risks by wrapping the frozen hot water bottle in a towel and putting a waterproof mattress protector over your mattress.

Why Should You Freeze a Hot Water Bottle?

The reason people are freezing hot water bottles rather than just plastic bottles is that they stay cold for much longer. The rubber that traditionally keeps the water warm all night is just as efficient at keeping water cold.

This makes them ideal for keeping us cool in a heat wave, particularly at night when people struggle to sleep.

It’s also a great way to save money and energy. You may already have a hot water bottle in the house, and even if you have to go out and buy one, it’s likely to be less expensive than a fan and considerably less expensive than an air conditioning unit!

With fans and air conditioning, you also need to think about the cost of running them and the impact on the environment.

It’s not a good idea to give a frozen hot water bottle to your pet to help them keep cool. Pets could chew or scratch through the rubber and damage the hot water bottle, or more importantly, they could swallow some.

Some firms make cooling pads and bottles specifically for pets, so it may be a good idea to invest in some of these.

Can You Use a Frozen Hot Water Bottle on a Sports Injury?

Another potential use is for sports injuries. Ice is known to reduce pain, swelling and inflammation. Many people use ice packs or even a bag of frozen peas on an injury, but a frozen hot water bottle is another option.

It’s a good idea to do a little research into whether heat or cold would be better for your specific injury. Generally speaking, it’s best to use ice for new injuries and heat for muscle pain and stiffness.

Heat generally draws blood to the site, so it is better for use 72 hours or more after the injury.

Simply wrap the frozen hot water bottle in a towel and apply to the injury for up to 15 minutes.

If you have more questions about freezing hot water bottles then these FAQs might help out:

Is It Safe to Freeze a Hot Water Bottle?

Yes, it is perfectly safe, but the expanding water may damage the seal. Things can become dangerous if you use the previously frozen hot water bottle with boiling water. Keep a hot water bottle reserved solely for use in the freezer.

Can You Freeze Hot Water Bottles with a Cover?

If your hot water bottle has a furry, soft cover, then you’ll need to remove this before freezing it. This will become soggy otherwise.

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