But an increasing number of southerners are receiving severe burns from them, which has prompted warnings from the Accident Compensation Corporation (ACC).
ACC recorded 93 hot water bottle-related injuries in Otago and Southland in 2022 — the highest number in the past five years for the regions.
It was also 11% of the nationwide total.
In Otago, the injuries cost $33,000 to help people recover, and in Southland it cost $27,000 — almost four times the amount spent on the same injuries in the previous year (2021).
Nationwide in 2022, ACC accepted 856 claims for hot water bottle-related injuries, the majority of which came from burns (91%).
These injuries came at a cost of $730,000 to help people recover, and was the highest cost of the past four years.
Over the past five years, there were 4593 hot water bottle injury claims in New Zealand, costing $3.6 million.
Alongside hot water bottle injuries in 2022, 119 people were hurt in an electric blanket-related injury at a cost of $240,000, and 62 people were injured in a wheat bag incident, which cost $87,000.
ACC injury prevention leader James Whitaker said there was nothing better than being warm and cosy in bed when it was cold outside, but he warned hot-water bottles could be "really dangerous", especially when they were filled with boiling hot water.
"We know that suffering a burn injury can be a debilitating injury, and in some cases, a life-long injury."
He said each week, more than five children were burned severely enough to be admitted to hospital.
"For children and our older people, use the bottle to warm the bed, then remove it before the person gets into bed.
"We recommend never using boiling water to fill your hot water bottle because this can cause the bottle to split or leak.
"Make sure the top is firmly closed before using, and use a cover or wrap the bottle in a towel before using — this will help prevent burns."
He said it was important to check hot water bottles regularly for any splits or perishing, and if the bottle was damaged, it should be replaced with a new one.
"People should ensure their hottie has a safety stamp that looks like a daisy."
