Did you turn off the immersion?
The Irish mammy's catchphrase, about the switch for the hot water tank. Asked as you leave the house, as you board the plane and every time you ring home.
Did ye turn off de immersion? It's been on since Tuesday, we'll be bankrupt.

Shall I translate it into posh English for you, head?
Welcome aboard, dear thing. Here it is in posh English.
Did you switch off the water heater? It has been running since Tuesday. We shall be ruined.
Questions
What does did you turn off the immersion mean in Ireland?
The Irish mammy's catchphrase, about the switch for the hot water tank. Asked as you leave the house, as you board the plane and every time you ring home.
How do you use did you turn off the immersion in a sentence?
“Did ye turn off de immersion? It's been on since Tuesday, we'll be bankrupt.”
Updated
On the list: Irish slang phrases