How to check your hot water bottle is safe

Find the little-noticed symbols on them that hide the key info

In this cost of living crisis, the humble hot water bottle is making a comeback – often dug out from drawers and cupboards – helping people to stay warm without putting the heating on. However, while make do and mend works for many things, with hot water bottles safety comes first... and they have a shelf life. Use this little-known way to check how old yours is.

How long should a hot water bottle last?

The general recommendation is to replace your hot water bottle every two to three years.

This is the advice from manufacturers (reiterated by accident prevention charities and medical professionals) and it's likely for safety reasons. 

Most hot water bottles are made out of rubber (some are made from polyvinyl chloride, commonly called PVC), and rubber does degrade over time and with usage. Yet the recommended longevity of hot water bottles isn't explicitly outlined in the British Standard (BS1970:2012) that manufacturers must meet to legally sell hot water bottles in the UK.

According to an Australian study on hot water bottle safety, out of over 100 hospital admissions where burns from a hot water bottle were listed as the cause, over 80% were because the bottle had burst, split, or leaked.

So it's likely that manufacturers are erring on the side of caution in calling for an early replacement in order to minimise the chances of someone using a potentially dangerous bottle and it causing burns.

However, that's not to say a bottle that's less than two years old has no chance of splitting or leaking, or that any bottle over two years old will definitely be dangerous (Author's note: in researching this article, I found my hot water bottle was made in 2005 and has been used every year since then without issue).

A lot depends on how often you use it, how you store it and more (see below for how best to use and store hot water bottles).

How to check how old your hot water bottle is?

an image of a wheel split into 12 segments. 5 of the segments has 4 dots within them. The 6th segment has 3 dots. This means the bottle was made in the 3rd week of June 2018.

Every hot water bottle sold in the UK should have a 'flower wheel' on the funnel somewhere, which shows the date it was made...

  • The number in the centre of the wheel shows you what year it was made. For example, if it says 18, it was made in 2018.

  • There are also 12 segments around the centre of the wheel. Usually, the number of these segments that have dots in show you what month it was made. So, if there are dots in six sections, the bottle was made in June.

    We have seen others with dots just in one segment. For example, if there are dots in the third segment from the top, going clockwise, it was made in March. 

    Note: We've also seen a few bottles with multiple dots in seemingly random places. Manufacturer, LoveHotWaterBottles, suggests this might be due to factories using different moulds and therefore it's not clear which month and week it was made.

  • The number of dots in the final (or only) filled section shows which week of that month the bottle was made. So, three dots means the third week of the month.

Hot water bottle manufacturer, LoveHotWaterBottles, suggests that the manufacturing date isn't all that important and shouldn't be treated as an expiry date. It suggested to go by the date it was first used and always check your bottle for visible signs of wear or damage before using.

How to use your hot water bottle safely

Assuming your hot water bottle is in date, here are a few more tips on how to minimise the risk of burns...

Filling the bottle


  • Fill with a mixture of cold and hot water - Boil half the water needed and add cold water to the kettle or jug before filling the bottle.
  • Fill the bottle over the sink - Pour water into the bottle carefully to avoid spills.
  • Squeeze as much air as you can out of the bottle before stoppering it. If there's air left in the bottle, the water can heat the air, meaning it expands, which may burst the bottle.
  • Screw in the stopper until hand-tight - Ensure the stopper is securely in place.
  • Check the bottle for leaks - Regularly inspect the bottle to ensure it is in good condition.


  • Don't use if cracked, worn, or leaking - Ensure the hot water bottle is in good condition before use.
  • NEVER fill with boiling water - Using boiling water can cause damage and lead to the bottle bursting.
  • Don't use the microwave or oven - Avoid heating the hot water bottle using these methods.
  • Don't use hot water from the tap - Copper from pipes can affect the rubber's strength.
  • Don't fill more than two-thirds full - Unless the bottle is designed to be fully filled, avoid exceeding this limit.

Using the bottle

  • Don't place in direct contact with your skin, always have a cover, towel or clothing.
  • Don't put pressure or weight on the bottle, it's not designed for you to sit or lie on it.
  • Don't sleep with the bottle in bed overnight, remove it once the bed is warm before you go to sleep.    

Storing the bottle

  • Empty the bottle and hang it upside-down to drain. Make sure it's totally dry before storing it.
  • Store the bottle with the stopper removed.
  • Store it in a cool, dry, dark place.
  • Either hang it upside down or lie it flat to store it.
  • Don't place anything on top of the bottle while it's being stored.

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