By Porter Lang
Find the neck. Look just below the stopper, on the rubber. There should be a small circle that looks like a daisy, with a number in the middle and a ring of segments around it. That mark tells you when the bottle was made. What the sources do not agree on is what to do with that date.
What the mark is
RoSPA, the safety charity, says most hot water bottles have a date wheel, “a small circular mark that resembles a daisy”, usually stamped near the neck, and that it indicates the month and year of manufacture. That article is dated October 2025. It also says that as bottles age the materials can degrade, which raises the risk of splitting or leaking, so older ones should be checked and replaced regularly.
How to read it
The retailer Boots, on its health information pages, gives the method. The number in the centre is the year. The segments around it stand for the twelve months, with January the first segment from twelve o’clock and the count running clockwise. The segment that holds dots is the month of manufacture, and the number of dots gives the week. Boots offers an example: a centre marked “22”, no dots in the first segment and three dots in the second means the third week of February 2022.
Australia’s product safety regulator, in its own guide, says the same about the dots: each dot in the final dotted segment marks a week of that month. Two sources, one reading. Boots adds that the wheel is “mainly used by the manufacturer for traceability”. Our reading of that: the mark was put there for the factory first and the buyer second.
What the date is for
The wheel records when the bottle was made. Makers and retailers give different guidance on how long to keep one, so follow the instructions that came with your bottle.
What kind of sources these are
RoSPA is a safety charity. The Australian guide comes from a government regulator and is written for Australian shoppers. Boots and the two other retailers sell bottles and have an interest.
Questions a buyer would ask
Where is the date wheel, and which month and year does it show? Does the maker say how long to keep the bottle? We give no prices and no advice on any brand.
What we left out
We left out microwaveable warmers, electric bottles and every brand and every product.
Quick answers
Where is the date on a hot water bottle? On the daisy-like wheel near the neck, according to RoSPA. It shows the month and year of manufacture.
How do you read the daisy wheel? According to Boots, the centre number is the year, the segments are the months clockwise from twelve o’clock, and dots in the last segment give the week.
How often should you replace a hot water bottle? Makers and retailers differ. Follow the instructions that came with your bottle.
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