A DIY cooling hack using a frozen water bottle and a fan can help Britons beat the extreme heat as temperatures are forecast to reach 40°C this week, potentially breaking the June record of 35.6°C set in Southampton in 1976.
The Met Office has issued a rare red weather warning for extreme heat across central and southern England and Wales on Wednesday, June 24, and Thursday, June 25. With only around four million UK households equipped with air conditioning—double the number from three years ago—millions of residents are seeking ways to stay cool.
How the DIY Air Conditioner Works
Katie Mortram documented her experience on Good Housekeeping, using two common household items: a one-litre water bottle (or a four-pint milk bottle) and water. She filled the bottle 75% full and froze it solid. Once frozen, she placed the bottle in a shallow tray to catch condensation, covered it with a moist cloth, and positioned it directly in front of an electric fan.
Mortram noted that the water expanded to the lid and pushed out the bottom of the packaging, making it difficult to stand upright. However, the packaging did not crack. She reported: “I wasn't sure it was doing anything at first, but the breeze in front of the bottle definitely had a slight chill to it compared with the breeze between it and the fan.”
Results and Limitations
Within two hours, Mortram felt a significant cooling effect. The bedroom became noticeably cooler and airier than the hallway, which felt stuffy and stagnant. She noted that the ice melted completely after four hours, limiting the hack’s duration. However, four hours of relief could be invaluable during the hottest part of the day.
Mortram acknowledged the energy costs: freezing the water and running the fan consumed electricity. She concluded: “While it's a limited quick fix, I can confirm that this method does work when needed.”
Safety Warnings
There are important caveats. The tray of ice and water must be placed at least 30 cm away from the fan to prevent electrocution if the fan topples over. Additionally, the NHS warns that when indoor temperatures exceed 35°C, fans should not be directed at the body, as they can circulate air hotter than skin temperature, accelerating dehydration. Instead, aim the fan away from your body to cool the surrounding air.
