The Mughal Water Container is a treasure that can be found in Uncharted 4: A Thief's End, in Once a Thief...

Location: Edit

This is the first treasures in this Chapter. Before you grapple hook to the rocky wall when Sam gives you the grapple hook. Go to the oppsite side of the grapple hook area (the far left side of the cliff) and the treasure is on the cliff.
Far left side of the cliff