How old can a hot water bottle be?

With regular use, a hot water bottle lasts around three to five years, and that span counts from the time you start using it. So if yours says 2023 and has been sitting unopened in a cupboard since then, it is not automatically almost used up.

Every material ages, cupboard or not. The question is how fast and under what conditions. That is why the answer depends less on the year than on the state your bottle is in.

The year on the bottle is a production date

Hot water bottles carry the year they were made. It tells you when the bottle was manufactured and makes it possible to trace which production it came from. It has nothing to do with a best-before date on a food package. 2023 means made in 2023. It does not mean that 2026 is the end.

A cupboard is not the same as daily use

A bottle in use gets filled with hot water again and again. It expands, cools down and contracts, gets strapped on, squeezed and laid flat again. Those cycles are what wear the material down, and they are what the three to five years refer to.

An unused bottle goes through none of that. It lies there empty and cold, nothing stretches, nobody presses it together. So you cannot simply subtract the time in the cupboard from its service life.

What decides how long it lasts

Four things make the difference:

• how often you use it
• how hot you fill it, boiling water ages the material faster
• how you store it in between
• what condition the material is in by now

Two of those are up to you. Our guide to filling it goes through that in detail.

Why our bottles are made of PVC

Our hot water bottles are made of PVC, free from phthalates. PVC ages differently from natural rubber, which many classic hot water bottles are made of, and it copes well with longer storage.

The stopper usually gives up first

When a hot water bottle starts to leak, it is usually at the stopper. The seal inside it hardens over time while the bottle itself holds up longer. Close the stopper firmly but without force, and look at it now and then. If it looks brittle or no longer grips cleanly, it needs replacing. We keep replacement stoppers in the shop.

Take a look before you fill it

Whatever the year says, give it a quick check before the hot water goes in:

• no cracks, including along the folds
• no deformation
• no brittle or sticky patches
• stopper sits tight and keeps the water in

If you spot any of that, stop using the bottle. And to keep it from getting there: store it empty, open and dry, with nothing heavy on top. Otherwise creases stay in the material, and that is where it eventually cracks.

Hot water can cause burns. Please do not use boiling water, and use the hot water bottle only in its cover or in the belt it comes with.