When pilots pour water, it is often for practical or traditional reasons:

1. Testing Cabin Pressure or Seals: Pilots or maintenance crews might pour water around cockpit windows or doors to check for leaks in the pressurization system. If water seeps through, it may indicate a seal issue.
   
   

2. Clearing Windscreens: On smaller aircraft, if no windshield wipers are available, pilots sometimes pour water over the windscreen to remove dirt or improve visibility during preflight inspections or while parked.
   
   

3. Aircraft Cooling: In hot climates, water can be poured over certain parts of an aircraft (e.g., tires or brakes) to cool them down if they have overheated during operation.
   
   

4. Superstition or Rituals: In some cultures, pilots pour water on a new aircraft or after a successful first flight as part of a ritual or blessing.
   
   

If you’re referring to a specific instance or practice, let me know, and I can elaborate further!