Electric blanket or hot water bottle? Heating experts settle the safety and cost debate for this winter

It usually hits on a Tuesday night, when the forecast quietly slips to 0°C and the heating timer becomes a moral dilemma rather than a button. You stand in the hallway with one hand on the thermostat and the other on the cupboard door, weighing up the reassuring heft of a hot water bottle against the plug-in promise of an electric blanket. One feels old‑fashioned but familiar, the other efficient but faintly worrying, as if the socket might have an opinion about it.

This winter, with energy prices still stubborn and headlines full of “stay warm for less”, the choice stops being cosy and starts feeling strategic. Is that hour of electric heat cheaper than a kettle’s boil? Is rubber and boiling water really safer than a modern blanket with a dozen approvals? I spent a damp afternoon with heating engineers, fire officers and an energy adviser, putting numbers and real‑world habits where the worries live. One quiet truth emerged: what you use matters less than how you use it.

The real cost: pennies, not pounds – if you time it right

Cost is the question that gets whispered first. On paper, electric blankets are frugal. A typical under‑blanket for a double bed uses about 40–70 watts on a low setting. At around 28p per kilowatt hour, that’s roughly 1–2p per hour, about the same as leaving a low‑energy lightbulb on. If you pre‑warm your bed for 30 minutes and turn it off as you get in, you’re spending less than a teabag.

A kettle, by comparison, is a sprinter. At 2–3 kW it burns through energy quickly, but briefly. Boiling a full kettle for two hot water bottles might use 0.1–0.15 kWh if you fill it sensibly, which works out around 3–4p. The catch is that nobody boils a perfect amount every time, and some heat escapes into the room instead of your bed. Still, for a couple of bottles, you’re typically under 10p a night, not a small fortune.

One energy adviser in Manchester put it this way as he checked a staircase full of chilly student houses:

“A low‑watt electric blanket used for an hour costs less than reheating a cold room for the same comfort. You’re heating the person, not the space.”

The key difference is pattern. An electric blanket quietly sips power for as long as it’s on. If you’re the kind of person who drifts off and forgets to switch it off, those pennies creep. Hot water bottles, once filled, are done; the cost is locked in with the lid.

Safety: modern tech versus very old habits

Here’s where the conversation changes tone. Fire investigators are blunt: both electric blankets and hot water bottles feature in winter accident reports, but for different reasons. Modern blankets sold in the UK must meet strict safety standards, include overheat protection and often have automatic shut‑off timers. The risk usually comes not from the device itself, but from age and neglect.

Frayed cords, creased elements, blankets that are over ten years old and still folded in the airing cupboard like old maps – these are the ones that cause trouble. If the fabric is thinning, the connections feel loose, or there’s any scorch mark at all, it’s retirement time, not “just one more winter”. Plug‑in adapters stacked on extension leads add another layer of risk, especially under beds.

Hot water bottles, for all their grandmotherly charm, carry a quieter danger: scalds. Rubber perishes with time; seams crack, stoppers wear, and a bottle that looks fine at a glance can fail suddenly when filled with boiling water. Burns services see a spike every winter from bottles pressed to bare skin, tucked against children, or filled straight from a roaring kettle without letting it cool a beat.

One fire officer in Bristol summed it up while holding a basket of surrendered relics:

“Old electric blankets cause fires; old hot water bottles cause burns. The safest option is the one you’ve inspected this year, not the one you’re sentimentally attached to.”

The human mistake is the same on both sides: we trust things because they’ve “always been fine”, long after the materials disagree.

How to use them so they help, not harm

The most useful advice from the experts wasn’t “choose this one”, but “stack small habits”. Electric blanket manufacturers and fire brigades repeat a similar rhythm. Lay the blanket flat, never folded or scrunched. Use it on top of a mattress protector, under a fitted sheet, not under heavy toppers that trap heat. Check the cable for nicks and the controller for rattles every time you strip the bed. Most importantly, use a timer: pre‑heat for 20–30 minutes, then either switch it off or set the auto‑off for an hour.

With hot water bottles, the choreography is almost ritual. Check the date stamp: anything over five years old is a candidate for replacement, sooner if the rubber feels sticky, thin, or cracked when you bend it. Fill from a kettle that’s just boiled but has been left for a minute; you want hot, not volcanic. One hand on the neck as you pour, no more than two‑thirds full, then squeeze the air out gently before sealing. Always wrap it in a cover or towel and keep it off direct skin, especially for children and people with reduced sensation, such as those with diabetes.

Let’s be honest: nobody does the “bend test” on every bottle before a film night, or inspects every stitch on the blanket twice a week. So choose a trigger. Make checking dates and wires part of changing to winter duvets, the same weekend you dig out scarves and silently swear at the attic.

Person, not product: matching heat to how you live

Once we stepped away from lab numbers, a pattern emerged. Electric blankets shine for people who struggle to get warm through – older adults with poor circulation, those who feel the cold in their bones rather than on their skin, and anyone trying to keep the heating off overnight without waking at 3am in a shiver. The steady, low background warmth across the whole bed can mean fewer layers, less tossing, more actual rest.

Hot water bottles play a different role. They’re a targeted comfort: a hot weight at cold feet, a warming press on a sore back, a portable heat source you can move from sofa to bed without trailing a cable. For children, the ritual of “filling the bottle” with a parent can be as soothing as the heat itself, provided adults handle the kettle. For renters wary of old wiring or limited sockets, they feel less like a gamble.

Think less in terms of “which is better” and more like this:

• Electric blanket: best for pre‑warming the whole bed, steady low‑cost heat, people who need consistent warmth.
• Hot water bottle: best for spot‑heating, portability, quick comfort without plugs, households nervous about leaving anything electrical on.

For some households, the sweet spot is both: a blanket on a low setting to take the edge off the mattress, plus a sensibly filled bottle at the feet, and the central heating turned down a notch without anyone resenting it.

Quiet rules that make a big difference

If you like clarity, here’s a compact guide you can pin to the fridge or screenshot for later.

Point	Detail	Why it matters
Cost in use	Electric blanket ~1–2p/hour on low; hot water bottle ~3–8p per fill	Helps budget without giving up comfort
Safety checks	Replace electric blankets after ~10 years; bottles after ~5 years or at first signs of wear	Cuts fire and burn risk dramatically
Smart habits	Timers for blankets; cooler‑than‑boiling water and covers for bottles	Real‑world routines that people can actually keep

FAQ:

• Is an electric blanket cheaper than turning the heating on? Often yes, if you’re heating one bed instead of a whole room. A low‑watt blanket for an hour can cost pennies, whereas raising room temperature several degrees for the same comfort usually costs more.
• Can I sleep with the electric blanket on all night? Many modern models are designed for overnight use with safety cut‑offs, but experts still suggest using the lowest setting and the timer. If you’re worried, pre‑heat the bed, switch off as you get in, and rely on duvets and layers.
• Are hot water bottles safe for children? They can be, but adults should always fill them, use a thick cover, and keep them away from very young children or anyone who can’t move them if they feel too hot. Lukewarm rather than very hot water is safer for kids.
• Can I use an electric blanket with a memory foam mattress or topper? Check the mattress and blanket instructions. Some foam products don’t like prolonged direct heat, but most are fine with low settings and pre‑warming rather than constant use.
• What’s the quickest way to tell if my hot water bottle needs replacing? Bend it in good light and look closely at the neck and seams. Any cracks, whitening lines, thinning, or sticky texture are signs to bin it. If you can’t read the date stamp, assume it’s time to upgrade.

The quiet win, experts agreed, isn’t choosing a side in some cosy war. It’s deciding, once, how you want to feel in your own home when the frost settles – and then giving that plan decent tools and five minutes’ attention before the real cold arrives.