Consumer experts at Which? have warned households to check the hidden daisy wheel symbol on hot water bottles, as older products are more likely to burst or leak and cause serious burns.
The warning comes as autumn temperatures drop and many people consider using hot water bottles to stay warm while keeping energy costs down. Which? noted that hot water bottles have a short lifespan and that the older they get, the more likely they are to burst or leak.
What is the daisy wheel?
The daisy-like symbol features a central number indicating the year the bottle was manufactured. Which? said: "This symbol means that I should have thrown away this hot water bottle years ago. See, hot water bottles have a short lifespan. The older they get, the more likely they are to burst or leak."
According to the Children's Burns Trust, cited by Which?, if a bottle is more than two years old, it is too old. To check the date of manufacture, owners should look for the daisy wheel symbol. Which? said: "According to the Children's Burns Trust, if yours is more than two years old, it's too old. To make sure, you can check your bottle's date of manufacture, just look out for this handy daisy wheel symbol."
How to read the symbol
Which? explained: "And if you want to be more specific, the petals represent the twelve months of the year and the dots are the weeks in those months." In one example, the daisy displayed a central number of 25, confirming it was produced in 2025, while a 26 would indicate the bottle was made this year, and so forth. The daisy features 12 petals with a series of small dots within them.
Should two petals contain dots, seven in total, this would indicate the bottle was manufactured in the third week of February. However, the daisy wheel does not serve as a definitive expiry date, as the longevity of the item depends largely on how it is used and maintained.
Replacement and disposal advice
According to MoneySavingExpert, the widely accepted guidance is to replace hot water bottles every two to three years. MSE explained: "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."
Failing to replace a hot water bottle regularly could result in it bursting, potentially causing serious burns. Any bottles showing signs of cracks or tears should be replaced straight away. Which? advised: "Remember to always check your hot water bottle before you use it for signs of wear and tear, like split seams, perished rubber and a poorly fitting stopper."
Old hot water bottles can often be recycled. Which? said: "Old rubber hot water bottles can be recycled, but double check with your local council to see if they can go in your household recycling bin."
