Pouring water, this way that way - something that is not very new to DD1. She had done various versions of it without getting bored. Here is another time she wants to do the same activity with different arrangement of vessels and actions.
So, it was dinner time just when DD1 grabbed hold of different types of glasses(and chembu in local language) and asked for water in them. What did I do?
Arranged tray on the dinner table with all the vessels that she brought. Filled one of them with water and asked her to do the following:
Pour some water into the smallest glass
Now empty the smallest glass
Pour some water in biggest glass
Pour some water in each of the glasses one after the other
Empty the biggest glass
Empty one of these three glasses- any one( she would choose)
Empty all the glasses
Mix water of these two glasses
All the while, she is reminded to pour water carefully without dropping any.
Next time your child asks for any item that seem to be messy, offer an activity out of them. Do not bluntly say no and discourage their sense of exploration.