![Why You Should Never Use Boiling Water To Fill Your Hot Water Bottle [3 Minute Read]](http://thehotwaterbottlecompany.com/cdn/shop/articles/Why_You_Should_Never_Use_Boiling_Water_To_Fill_Your_Hot_Water_Bottle.png?v=1762259631&width=1100)
Hot water bottles are a comforting winter staple, perfect for warming the bed, easing aches, and providing cosy relief. But did you know that using boiling water to fill your hot water bottle is unsafe?
This isn’t just a general suggestion. It’s a clear instruction from the British Standard for hot water bottles: BS 1970:2012, which states:
“When filling this hot water bottle do not use boiling water.”
So why is this rule so important and what should you do instead? Let’s break it down simply so you can enjoy your hot water bottle safely and confidently.
Why Boiling Water Should Never Be Used
It may seem harmless to pour freshly boiling water straight from the kettle into a hot water bottle. After all, the hotter the better… right?
Actually: wrong.
Here’s why.
1. Boiling Water Is in an Active State
When water is boiling, it is rapidly transforming from liquid into gas (steam). This physical process causes bubbles of vapour to form throughout the water and surge upward to escape. This movement is not just on the surface it happens throughout the entire liquid.
When you attempt to pour this bubbling, steaming water into a container such as a hot water bottle, the trapped air inside tries to escape. The only way out is through the opening and this can cause:
- Splash back / Uncontrolled surging which can lead to scalds or burns.
This is exactly what often happens when people report that “boiling water pushed out” of the bottle as they tried to fill it.
It’s not a product fault - it’s just physics.
2. Boiling Water Damages Rubber
Hot water bottles are made to safely hold hot water, not boiling water.
Boiling temperatures can:
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Soften and weaken the rubber
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Damage seams or seals
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Shorten the product’s lifespan
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Increase the risk of leaks or splits
Even a compliant, high-quality bottle can be compromised if misused.
3. It Can Lead to Serious Injury
Most hot water bottle burns happen during filling or from leaks caused by weakened material.
These accidents are easily avoidable when the instructions are followed. If boiling water is used, any resulting burns occur as a direct result of not following safety instructions, rather than any product defect.
How to Fill a Hot Water Bottle Safely
Here’s a step by step guide to preparing your hot water bottle in the right [and safe] way:
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Boil the kettle.
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Allow the water to cool for a few minutes - we recommend at least 5 minutes.
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Hold the bottle upright by the neck
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Slowly pour water into the bottle [Fill no more than two-thirds full]
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Gently expel any excess air by lowering the hot water bottle onto a flat surface until water appears at the opening.
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Insert the stopper and secure it firmly, to ensure there is not leakage
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Check for leaks
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Use a cover to avoid direct skin contact
Why “Hot but Not Boiling” Is Best
Letting boiled water cool slightly means:
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The water is still warm and comforting
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It is no longer in an “active”, bubbling state
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The risk of splashback is dramatically reduced
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The bottle is protected from heat damage
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You can enjoy the benefits safely
Keep The Instructions
BS 1970:2012 requires that instructions supplied with compliant hot water bottles advise consumers to keep them for future reference.
The instructions for use are designed to help you:
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Use your product safely
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Avoid injury
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Prolong your bottle’s life
If someone uses boiling water despite these instructions, any resulting injury is due to misuse, not a product defect.
Final Thoughts
Hot water bottles are simple, safe and effective when used correctly. Following BS1970:2012 guidance, particularly “Do Not Use Boiling Water”, helps protect you from avoidable injury and keeps your bottle in good condition for longer.
By taking just a moment to let your water cool and fill your bottle carefully, you can enjoy warmth and comfort with complete peace of mind.
Stay safe, stay cosy!
The Hot Water Bottle Company Team x
Watch our safety video on how to fill, use and care for your hot water bottle