It began here in the capital several weeks ago when the sunny weather set in. And it will carry on claiming life after life after life, just as it does every year, until the autumn chill returns around the beginning of September.
By the year's end, the national death toll is certain to match the 10,000 people who - according to initial British estimates - have died in Serb atrocities in Kosovo. But you can be sure there will be very few headlines.
Russians have long become used to the idea that every summer many thousands of drowned corpses are fished out of the rivers, lakes and waterways, adding momentum to the precipitous decline of their 146m population. In a particularly hot week earlier this month, 70 - yes, seventy - people drowned in the Moscow region alone, a statistic that covers just a fraction of this gigantic nation.
Ask Russians why this phenomenon occurs, and they tend to give a dismissive tap to the side of their throats with a forefinger - a despairing gesture that is in constant use here as it means drunkenness. Russian men, they wearily explain, have a tendency to go out for a day in the sun, get hopelessly hammered, and plunge into chilly water - where they perish, through heart failure, or by falling unconscious, or because the drink has beguiled them into a macho attempt to swim far further than they actually can.
Boys, fatally, will be boys. Officials confirm that the vodka bottle plays a dreadful role, saying (with that curious Russian love of precision in an otherwise opaque world) that 62 per cent of those who drown are drunk. One in five are children (a reflection, perhaps, of the shortage of funds which has caused cuts in school swimming lessons.)
But it is not as simple as that. Moscow is not a city where you can easily pop down on impulse to the local municipal baths for a dip when the weather becomes too oppressive (as it frequently does; most people live in tiny, stuffy flats which are designed to keep in the heat).
Seventy of the city's 110 pools have closed in the last few years, through shortage of funds. And to get into the remaining few, you often have to negotiate a path through a maize of old Soviet rules which include having a medical examination. Great care is taken to protect the nation from catching verrucas from walking beside swimming baths; less, it seems, to stop it from drowning en masse outdoors.
To check whether these rules still applied - and on a particularly hot and sweaty day - the Independent on Sunday this week called a Moscow polyclinic, Number 157. The news was grim. To get a certificate to swim - known as a spravka - we would have to go to a doctor (which means queuing), who would send us for blood and urine tests (more appointments; more queuing). The test results take about a week. A trip to a dermatologist might also be necessary to check for fungal growths and - get this - in some cases even a gynaecologist. The resulting certificate would be valid for two months.
It is said here that "every Russian fence has a hole in it", and the way to find it is usually by fishing out dollars. If you are prepared to pay, you can by-pass the spravka system by using pools at some of the city's swishest hotels. But the prices can be horrendous: it costs $30 for one adult ticket to swim at Moscow's Mezhdunarodnaya Hotel at the weekend. The clientele represent the tiny minority in Russia with money to squander: close-cropped, young Russian "businessmen", wearing thongs and gold chains, swagger around the poolside with their elegant, minimally clad girlfriends.
Finding a new pool with reasonable prices and no silly rules is much like striking oil. "Discovered a great outdoor place," a British friend of mine announced the other day, when the thermometer was just topping 32C (89F). "It only costs 150 roubles (pounds 4) for a whole day, and no doctor's certificate," he boasted. But there was a long, embarrassed silence when I asked him exactly where it was. "Er, you know, we don't want it to get too crowded," he explained.
How much easier it is for Muscovites to head out to one of the many natural, deadly, watering holes in and around the capital where you can bathe in the open air, free from regulations and mafia men. Better still, pray for cold and rain.