A water main is an underground pipe that delivers water to a resident’s service pipe. In residential areas it usually runs under the street. If a hole or crack develops in the pipe, the water will typically find its way to the surface. Because the water main is under pressure, water will continue to flow until the break is repaired.
Water main breaks are more likely to occur when frost penetrates deep into the ground, to a level of 3-5 feet, usually from late January until early April. While cold temperatures may send the frost deeper, the level of snow cover is also important. Snow will act as a "blanket" insulating the ground. In years when there is plenty of snow, the frost does not go as deep.
If water needs to be turned off for a water main break, homeowners will receive little or no notice. The water can flood streets and private property causing damage and safety hazards, and must be controlled as quickly as possible.
At that time a boil order will be issued, and water sample(s) will be taken for testing in keeping with EPA standards.
Boil Water Order Guidelines(PDF)