Experts at vehicle leasing specialist Cars on Demand say pouring hot water can “crack or shatter” glass within seconds. They warn hot water can also risk heavy damage to a car’s paintwork as the water runs down the side.
Experts at the AA warn even warm or lukewarm water can lead to massive damage and urge road users to avoid using it.
They warn glass expands quickly when warm water touches it before contracting quickly when it cools down.
This flexing can lead to even small cracks which can get bigger over time.
However, the AA poll found 23 percent of road users used warm water to clear their windscreen despite this carrying a risk.
This will clear frost and ice cover while preventing the water itself from touching and damaging the glass.
They added: “A quick and effective hack to de-ice your windows, wing mirrors and windscreen is to fill a food bag (or something similar) with warm water and carefully move it across the icy areas of your car and watch the ice melt quickly.
“It is best to use warm water from the tap as it is easier to hold in the bag and prevent the glass from shattering.”However, young people were more than twice as likely to use boiling water with one in 20 risking a cracked windscreen.