water

You can lead a horse to water, but you can't make it drink

• water off a duck's back
• to be water under the bridge -something is in the past and no longer important
  

• to make your mouth water- when something smells or looks so good that makes you feel like eating it, hence causing you to salivate

Adam´s ale = water in Restaurant diner lingo

drink

You can lead a horse to water, but you can't make it drink