In the depths of winter, one has to be careful of water lines to make sure that they don't freeze. Fixtures that get constant use you'll notice right away when there's an ice plug but it's fixtures that you don't use all the time that can be more dangerous, when it warms up the ice will melt and if the pipe burst, you'll end up with a huge water cleanup.
There is a couple things that you can do to prevent and detect problems. To help prevent any water lines from freezing make sure that you heat is working properly and distributing to rooms to keep the temperature above freezing. Space heaters in rooms can be dangerous if left unattended and as such aren't a good option. If you have an alarm system that supports it buy a freeze sensor to let you know if a room's temperature is getting too low and in danger of freezing. Also, a good practice is to have a water sensor in rooms or cabinets with water connections to let you know if a pipe has burst or if you have a leak from a connection at any time of year. Some money spent in prevention and detection can save a lot of money and time in water cleanup.