Expressions about water are almost as common as water itself.

But many of the expressions using water have unpleasent meanings. The expression"to be in hot water" is one of them. It is a very old expression. "hot water" was used five hundred years ago to mean being in trouble. One story says it god that meaning from the custom of throwing extremely hot water down on enemies attacking a castle. That no longer happens. But we still get in "hot water". When we are in "hot water",we are in trouble . It can be any kind of trouble -serious,or not so serious. A person who breaks a law can be in hot water with the police. A young boy can be in hot water with his mother,if he walks in the house with dirty shoes