Plane water is gross
If you get a drink, then make sure that it's not tea or coffee. The water used to make your beverage likely comes from the plane's water tank, which is under the plane and probably isn't very clean.
"The water from the plane is disgusting," an anonymous flight attendant said. "I feel truly sorry for our coffee and hot water drinkers. That water is in a tank under the plane and I've never seen that tank be cleaned out."
You might be better off sticking to bottled water.