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Why Did My Hot Water Bottle Burst? 6 Possible Reasons

Updated: Jan 21, 2023

hot water bottle burst illustration

Hot water bottles can burst if they have too much water or too much air in them. In addition, sitting, standing, or laying on a full hot water bottle exercises too much pressure on it, which can also lead to bursts. To prevent bursts, you shouldn't use hot water bottles after their expiry date. Damaged or leaking ones should be replaced, even in the case of minor leaks.

6 reasons why your hot water bottle could have burst

1. It had too much water in it

Manufacturers recommend filling hot water bottles up to two-thirds of maximum capacity. This prevents too much pressure from building up inside, which could lead to a "balloon effect".

If you fill your hot water bottle up to the top and accidentally sit on it or lay over it, it may burst due to excessive pressure (just like a balloon).

2. It had too much air in it

Bursts can also occur when too much air is trapped inside the hot water bottle, also leading to the balloon effect. This is why you should make sure to gently squeeze the air out of your hot water bottle when finished filling it.

Once filled up to two-thirds, gently lay your hot water bottle on the side and push the air out while bending the neck. Once all the air is out, screw the stopper on. Below are pictures of how your hot water bottle should look when properly filled.

Hot water bottle filled too much

blue hot water bottle

3. It had expired

Hot water bottles all have an expiry date. Past this date, they are more prone to leaks and bursts. This expiry date is indicated on your hot water bottle by means of a daisy wheel, a stamp showing the year, month, and week your item was produced.

The lifespan of a hot water bottle usually ranges between 2 and 5 years depending on the brand. This also depends on how well you store your hot water bottle and whether you use a cover for it.

daisy wheel explained

4. It was misused

Hot water bottles can burst if you sit, stand, or lay on them. This can happen especially if you filled them too much or trapped too much air inside of them. This is one of the reasons you shouldn't sleep with a hot water bottle.

Hot water bottles can be used by being placed on top of your stomach, arms, legs, or your chest for example. By placing it on top instead of underneath your body, no pressure is exercised on your hot water bottle, which decreases the chances of it getting damaged and bursting.

5. It was already damaged

Your hot water bottle could have burst because of an existing leak or scratch. This brings us back to pressure: if for instance, you (accidentally) sit on a damaged hot water bottle, it could easily burst.

This is why you should identify the source of hot water bottle leaks immediately and dispose of a leaking hot water bottle if necessary.

hot water bottle and tools icons

6. You tried to fix a leak yourself

If you found a leak, tried to repair it yourself and the bottle burst in the following weeks, don't look further, this is the reason. Hot water bottles are manufactured under very strict safety standards, which you cannot reproduce at home.

This means that if you attempt to fix it, your solution to the leak will probably not be sustainable. As explained above, even a minor hot water bottle leak leads to bursts. Read our full article on why you shouldn't fix a leaking hot water bottle yourself and the rare case when you can fix it.


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