Idioms: water related

to hold water:

it's sensible,the saying is believable and strong.

---the excuse simply doesn't hold water.

---The accused man claimed that he'd been in another city the night of the murder,but his story didn't hold water after three different witnesses testified in court that they had seen him running from the scene of the crime.

water off duck's back

no any effects,doesn't work;

----I keep telling my friend it's follish to gamble all of his money,but it's like the water off duck's back.

---The doctor tell us it's dangerous to smoke,but such good advice rolls off of some peoplelike water off duck's back.

It makes my mouth water

something is very dilicious,that you can't help to eat or eager for them.

----The roast duck serviced by that restaurant is my favourite dish,it often makes my mouth water when i think about it.

---my mother's cooking is very good,whatever she cook can make my mouth water .(can i make a sentence like that?)