MOSCOW — City governments across Russia drained the water from municipal fountains on Thursday, hoping to keep drunken paratroopers from drowning in them.

Aug. 2 is Paratrooper Day in Russia, and every year more than a million burly active and retired soldiers take to the streets in their signature blue berets and striped undershirts to mark the occasion, often by combining large quantities of vodka with plunges into fountains.

President Vladimir V. Putin seemed to call for restraint on Thursday, but with a barely concealed smile, during public remarks to paratroopers in Ulyanovsk. “I hope that Paratrooper Day will pass without excesses, and that your colleagues will behave themselves adequately, at least without gross violations of public order,” he said.

Officially, the day is celebrated with cadet marches and memorials. Unofficially, the elite troops start drinking at sunrise, then head off to city parks to brawl.