When the weather is extremely cold, water in rivers and reservoirs is also cold, and when it flows through the area's water distribution network, the pipes crack and break, and they have been doing it constantly over the past few days.
It is disruptive. Leaking water turns to ice on the streets. Repairs close down parts of roadways. Homes and businesses are sometimes forced to do without water.
Two minutes before midnight on Tuesday, the D.C. emergency alert system said that a water outage had been reported on Capitol Hill.
Quoting information from DC Water, the city's water utility, it said the problem was on C Street SE, between Delaware Avenue and South Capitol Street SE.
An 8-inch diameter main had broken, the alert said.
It said three government buildings could be affected. Restoration of service could take from eight to 10 hours, the alert said.
An earlier alert from the 3200 block of Pope Street SE said about 40 homes and two hydrants were affected by a break there.
Another, in the 1900 block of Massachusetts Avenue SE involved water supply to three apartment houses, with a total of 150 units. It was reported around 7 p.m. and plans called for completing repairs in the early hours of Wednesday.
It is hardly an exaggeration to say that mains have been breaking everywhere.
The Washington Suburban Sanitary Commission, supplier of water to Montgomery and Prince George's County, said Tuesday afternoon that it was "aware of of several water main breaks causing low pressure or no water" in or near the Temple Hills, Suitland, District Heights and Hyattsville neighborhoods
WSSC said it had responded since Friday to "more than 60 breaks around the area."
It said by Twitter with what appeared to be a degree of ruefulness that it was a "Good thing we have plenty of pipes in stock! "
Fairfax Water reported early Tuesday that it had 12 "active water main breaks" on its hands. A map showed them distributed over a wide area of Northern Virginia. Ten breaks were reported on New Year's Day.