We can't kiss the summer goodbye without introducing a reader named Susan Cook. She says piffle to road rage and in-flight rage. She's suffering from Metro rage -- because of several swigs of water.

Susan took those swigs on the morning of Aug. 2, while waiting for a subway train on the platform at Friendship Heights. She had just walked a mile to the station, through "heat and unhealthy air." She had already put her bottle of H2O back in her briefcase when "a very huge" Metro police officer approached.

He proceeded to write her a $10 ticket for drinking while in the transit system.

Susan has been a regular rider for eight years, so she is well aware of the rule against eating or drinking anything while on Metro. Still, as she pointed out to the officer, she hadn't littered and she hadn't splashed. He was unmoved. Nor did he care that Susan didn't intend to drink while aboard the train.

Susan thinks the officer should have gone 180 degrees in the other direction. Rather than treat her like a criminal, didn't she deserve thanks and praise for walking and using public transportation rather than driving when it was Code Red outside?

Susan thinks the officer could and should have given her a warning. Since he didn't, she offers one of her own: "Warn your readers!"

I already have, Susan, in a column about a similar case some three years ago.

In that episode, a jogger had just covered about five miles in the sweltering summer heat. She boarded a Red Line train at Dupont Circle and began to guzzle water from a jug. By the way, it was rush hour, so it wasn't as if this ball of sweat was riding by herself.

She, too, got a $10 ticket. She, too, thought she should have been coronated, not damned, for being so healthful.

Levey landed on her like a ton of bricks.

He castigated her for being selfish and for thinking the law didn't apply to her. He pointed out that the law exists not to harass joggers but to protect the rest of us in case a jogger spills water. If a jogger is so concerned about hydration, Levey blared, drink water before you board a train, not while you ride it.

I would have bet my last $5 that readers would have agreed. Wrong, as usual.

Readers insisted that there was a big difference between quaffing water aboard a Metro train and, say, eating a hot dog slathered with ketchup. They said, by the dozens, that Metro cops ought to ease up when only water is involved, especially during the summer.

I still have big trouble with that line of reasoning. If I'm doing some work aboard a train, why do I need to run the risk of having some jogger douse my important papers (or my hairdo, or my clothes, or my seat) with water?

The moaning and groaning reminds me of what we hear so often from speeders. Hey, they're all for enforcing the law -- until a cop whacks them with a $50 ticket for going 63 in a 55 mph zone. Then (and only then), the cop should have been lenient.

Anyway, the good news is that the Metro police are not rigid oafs. They have built a distinction into how they enforce the don't-eat-don't-drink law. It isn't a question of water being different from other food and drink. It's a question of regular riders being different from tourists and visitors.

Polly Hanson, deputy chief of the transit system police, told researcher Lynn Ryzewicz that officers are trained to ask if a violator is a Washingtonian. If so, officers ask if the violator is aware of the no-food-or-drink policy. Both sides agree that, in the case of The Great Bust involving Susan Cook, these were the first two questions the officer asked.

Polly Hanson said the underlying issue, as far as Metro is concerned, is litter, not stains. She said people leave all sorts of debris on trains anyway. If bottled water were allowed, they'd leave bottles and bottle caps. "Where do you draw the line?" the deputy chief said.

The only time Metro police relax water rules is on July 4, when the system is crammed with thousands of people, she said. She added that her department has received many more complaints about enforcement that's too lax than about enforcement that's too strict.

I don't wish heatstroke on Susan or any other sweat-producer. But at the risk of touching off zillions of letters once again, I still say:

Do your drinking before you enter the system. Or if you want to be really cynical, dress like a tourist if you're going to drink in the system.

More on liquids and Metro, starring Yours Truly. Since we're friends, I can admit it: I bollixed a fare gate with sweat.

This, too, happened during August. I was leaving the subway at Farragut North. I had stashed my Farecard in my shirt pocket. It was a horribly hot, humid day. My Farecard got a little, ahem, soggy. When I slipped it into the exit slot, the fare gate captured the card and turned it into ribbons of mush.

Bill Johnson, the station attendant, rescued the former card from the innards of the machine. Then he had me fill out a form, so that Metro could reimburse me for the $1.65 in value my card still possessed.

Bill also suggested that I warn readers that fare gates are very sensitive to moisture. I'm happy to take Bill up on it. From now on, on hot days, I carry my Farecard in my coat pocket, safe from sweat. Fellow riders, please copy.