Can you hold it another 20 minutes?

The reason our airlines seem to have cut back, not just on in-flight food but on drinks as well, offering us a few paltry ounces of soda in a plastic cup, may well have to do with the cost of the food and drinks.

On the other hand, I've heard it may have to do with security, considering that a canned item in a sock can cause some serious damage. I would guess that security is not the real reason, given the fact that a half-full soda can would at the very worst get someone wet.

But actually it turns out that cutting back on in-flight drinks might have to do with the cost of maintaining the rest rooms on board.

That is, if you can believe this story about a Chinese airline that "has calculated that it takes a liter of fuel to flush the toilet at 30,000 feet and is urging passengers to go to the bathroom before they board." You can just imagine the pre-flight safety instructions that the crew will announce over the P.A.: "In case of bladder emergency, a catheter will come down from the luggage rack above you. If you're traveling with a child, fasten your own before attempting to fasten it on the child." And to avoid subliminal suggestion, they'd have to eliminate (har!) the line about "the unlikely event of a water landing."

The article about the Chinese airline also says: "The company has asked logistics staff to fill the water tank only 60 percent full." Which I assume means water for the loo.

But I have absolutely no intention of finding out.