From The Expert: How Much Colder is Tap Water in the Winter?

You’re not imagining it: When you turn on that tap water in the dead of winter and it feels darn near freezing, it’s because it is.

Sure, everything seems a little colder once that winter chill sets in, but Patch checked with Steve Heimlich, the water plant manager at and he confirmed it. There can be a significant difference between cold tap water in the summer and the middle of winter when Lake Erie is almost frozen over.

“It depends on the temperature of the lake, our source water,” Heimlich said.

At the time of the interview Dec. 23, Lake Erie was 41 degrees. Residents and businesses can expect tap water on the coldest setting to be within a degree or two of that.

Heimlich said it all has to do with our water source, Lake Erie, which is affected by air temperature. The temperature can vary significantly from other water sources, such as underground sources.

“Eventually the water (in the lake) will get down to 33 degrees  Fahrenheit,” he said.

That is, until the lake gets an ice cover. Then in an anomaly of science, the lake temperature will slightly increase.

“Once Lake Erie gets an ice cover it will go up in temperature a little bit, to 34-35 degrees.”

Heimlich said the water plant, which sits off the shore of Lake Erie, does not heat the water. On its travels from the plant, which serves 180,000 customers daily, to the tap, the water might heat slightly, but not a lot.

“Natural underground temperature is 55 degrees Fahrenheit,” Heimlich said of water traveling through underground pipes. “It does warm a little bit, but not a lot. It stays pretty cold.”

Water treated by the Avon Lake plant comes from two offshore cribs. Water is transported through a 36-inch intake and 54-inch intake, each submerged 23 to 24 feet below the surface, depending on the depth of the lake.  The facility has the capacity to treat 40 million gallons a day.

Wintertime means the Utilities needs to pay extra special attention.

“When it gets to 39.2 on the surface the water becomes heavier,” Heimlich said. “That’s when water reaches its densest point.”

That’s when the phenomenon called “turnover” occurs and the top water cools and sinks.

“We get what’s called ‘frazil ice,’” Heimlich said. “The water starts to freeze. If surface is 34 and starts to cool and forms ice crystals, it can form a slush and go down into the intake. It can turn into a slushy down there.”

Heimlich said it’s optimal when the lake just freezes over.

So there’s at least one benefit to living up north in the winter. If you’re craving a glass of ice-cold water, just turn on your tap in the middle of winter. Cheers.