To prevent frozen pipes, leave a trickle of warm water running from a faucet on nights when the temperature drops. The slow flow of water prevents ice from blocking pipes and also prevents freezing damage. In addition, leaving under-sink cabinets open allows warm air to circulate around pipes and keeps their temperature from dropping into the freezing range.
Contrary to popular belief, leaving warm water running does not actually prevent ice crystals from forming inside pipes. Instead, it relieves the pressure that can build up when water freezes and keeps the ice crystals moving, allowing them to escape from the faucet and melt rather than consolidating in one place and forming a blockage.
In northern climes, pipes are usually built into the foundation of a home and are well insulated. Southern homes are more vulnerable to severe cold snaps, due to the fact that pipes are often run outside and left without protection. Any time the temperature drops lower than 20 degrees Fahrenheit, it creates the potential for freezing and burst pipes.
If freezing pipes are a regular problem, homeowners can add insulation to vulnerable sections of their plumbing. Areas where pipes and cables enter the foundation of a home are areas that can also let in cold air and should be sealed and insulated properly against the cold.