Metal thieves who stole copper pipe worth less than £30 from Southend Reform Synagogue caused a gas leak in the surrounding area.
Ten feet of copper pipe, which had been fitted just three months previously, was torn off in the early hours of last Tuesday.
The Westcliff-based community has since been unable to heat the building and has had difficulty finding a plumber because it is not an emergency situation.
A plumber was eventually booked to start repairs on Wednesday, but the synagogue will have to meet the £600-plus cost because of the impact on its no claims bonus if the expense was put through its insurer.
"People complain that it's cold in the building at the best of times," said synagogue caretaker Richard Levy.
He said that had it not been half-term when the leak occurred, the nearby street would have been full of children making their way to school the following morning.
The leak was not discovered until 10am.
It is the second time that the synagogue has been targeted by thieves. Lead was stolen off the roof last year. Local police are investigating the theft.