Source: Water and Language

• In deep water. 
• Water under the bridge.
• Still waters run deep.
• Hell or high water.
• Blood is thicker than water.
•  Taking on water.
• You can lead a horse to water but you can't make him drink.
• Water, water everywhere and not a drop to drink.
• A fish out of water.
• Don't make waves.
• Don't throw the baby out with the bath water.
• Wet behind the ears.
• The drop that makes a vase overflow.
• Drowning in a glass of water.
• To be in hot water.
• Filthy water cannot be washed. 
• “How could drops of water know themselves to be a river? Yet the river flows on.” ~ Antoine de Saint-Exupery
• “It is the calm and silent water that drowns a man.”
• “Water is the driving force of all nature.” ~ Leonardo daVinci
• When it rains, it pours.
• Walking on water. 
• Water doesn't run uphill.   
• Watered down.
• As uneasy as a cat near water.
• Plain as water.
• Makes your mouth water.
• Muddy the water.
• Like a duck out of water. 
• Just a drop in the bucket. 
• Hewers of wood and drawers of water.
• He has his head in the clouds.
• Get your feet wet.
• Every path has its puddle. 
• Either you sink or you swim.