A friend of mine was walking through McPherson Square not long ago when he noticed a public drinking fountain running. And running. And running. After watching about 10 gallons go down the hatch, undrunk, unsaved, untouched, he decided this was a waste. So he paid a call on Robert F. Levey, Friend of Fresh Water, to ask why.

The phenomenon turns out to be much less widespread than McPherson Square might lead you to believe. According to Don Heilam of the National Park Service, only four of the 65 public fountains in parks run by the federal government run all the time. And in each of those cases, there is a reason.

Take Hains Point, for example. It is such a long distance from the nearest pump to the fountain that the Park Service decided to let that fountain run all the time. If it hadn't, Heilam says, there'd be as much rust coming through the line as water.

In the case of another run-always fountain (Heilam couldn't remember the location), elderly residents of the area thought it would be more convenient if they didn't have to turn a handle every time they wanted a drink. So the Park Service obliged.

Heilam noted that run-always is often the only alternative to run-never. Handles are vandalized and destroyed so often, he said, that if you don't have a run-always fountain in your park, "you may wind up with nothing."