Expressions about water are almost as common as water itself. But many of the expressions using water have unpleasant meanings.

The expression “to be in hot water” is one of them. It is a very old expression. “Hot water” was used 500 years ago to mean being in trouble. One story says it got 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.

“Being in deep water” is almost the same as being in hot water. When you are in deep water， you are in a difficult position. Imagine a person who cannot swim being thrown in water over his head.

You are in deep water when you are facing a problem that you do not have the ability to solve. You can be in deep water， for example， if you invest in stocks without knowing anything about the stock market.

“To keep your head above water” is a colorful expression that means staying out of debt. A company seeks to keep its head above water during economic hard times. A man who loses his job tries to keep his head above water until he finds a new job.

“Water over the dam” is another expression about a past event. It is something that is finished. It cannot be changed. The expression comes from the idea that water that has flowed over a dam cannot be brought back again.

When a friend is troubled by a mistake she has made， you might tell her to forget about it. You say it is water over the dam.

Another common expression， “to hold water，” is about the strength or weakness of an idea or opinion that you may be arguing about. It probably comes from a way of testing the condition of a container. If it can hold water， it is strong and has no holes in it.

If your argument can hold water， it is strong and does not have any holes. If it does not hold water， then it is weak and not worth debating.

“Throwing cold water” also is an expression that deals with ideas or proposals. It means to not like an idea. For example， you want to buy a new car because the old one has some problems. But your wife “throws cold water” on the idea because she says a new car costs too much.

“to be in hot water” （ =to be in trouble）是一個使用時間很長的短語，早在500年前，hot water就被用來指遇到麻煩。關于這個短語的來源，有一種說法是源于一種傳統(tǒng)，當城堡被襲擊時，城堡里的人會用熱水潑向敵人。還有一種說法則是，過去一家的女主人碰到壞人闖入家中時，就會用熱水潑他將他趕出去。

“be in deep water”（be in a difficult situation which is hard to deal with）和“be in hot water”一樣，也是遇到麻煩、陷入困境的意思。試想，將一個不會游泳的人扔到水位高于頭部的深水區(qū)，這就真是一件麻煩事了。

“to keep ones head above water”（stay out of trouble， especially financial difficulties）是指避免陷入財務危機。游泳的時候，，要想自如地游動，首先要能夠把頭部抬出水面，這樣便可以邊游邊呼吸，不必擔心溺水。在水中遇到麻煩時，人們千方百計想做到的也就是讓頭部露出水面。短語keep ones head above water并不是真用來描述溺水者在水中掙扎的情景，而是用來比喻一種困境，尤其是因欠債而造成的困境，把頭保持在水面之上就等于使自己不陷入到債務的泥坑中去。

“water over the dam” （past and unchangeable events）是一個講過去已經(jīng)發(fā)生的事的短語。Dam是堤壩的意思，流過堤壩的水就無法收回了，這個短語用來形容已經(jīng)發(fā)生的無法改變的事實，也就是木已成舟、覆水難收的意思。

“to hold water”（to prove credible， logical， or consistent）從字面上理解，是抓住水的意思，可以理解為滴水不漏，引申為某人的觀點、理論等站得住腳。

“throw cold water”（to criticize or stop something that some people are enthusiastic about）這個短語從字面上就很好理解，是潑冷水的意思。