In countries with ambient temperatures below C, like Canada and?
Excellent question. The quick answer is that freezing temperatures only penetrate a certain distance into the ground. This is called the "frost line" (see Frost line). Water and sewer lines are buried below the frost line, and also enter the house below this line as well. In my location (Toronto) most water lines are about 5 or 6 feet deep. This is also a problem within the house. In cold climates, plumbing must never be run in an outside wall, because it can and will freeze. Contrast this with, say, England, where waste plumbing is often outside the house. Now, in the Arctic they have the opposite problem: the ground is permanently frozen (see Permafrost). In this case, lines are run in heated enclosures on top of the ground:(See Utility tunnel and Utilidors | Town of Inuvik) Edit 1/23/2015 to add: In smaller communities, there is no plumbing to the house. Water is delivered to each house by truck, and stored in an indoor tank. Waste water is also stored inside and collected from each house.