The American Red Cross gives the following tips to ensure your pipes don't freeze and even burst in the event of freezing temperatures:

• Keep garage doors closed if there are water supply lines in the garage.
• Open kitchen and bathroom cabinet doors to allow warmer air to circulate around the plumbing. Be sure to move any harmful cleaners and household chemicals up out of the reach of children.
• When the weather is very cold outside, let the cold water drip from the faucet served by exposed pipes. Running water through the pipe - even at a trickle - helps prevent pipes from freezing.
• Keep the thermostat set to the same temperature both during the day and at night. By temporarily suspending the use of lower nighttime temperatures, you may incur a higher heating bill, but you can prevent a much more costly repair job if pipes freeze and burst.
• Cover the exterior faucet with an insulated slip-on cover. This will prevent any remaining water from freezing. Exterior pipes should be wrapped with insulation tubing, which can be found at your local hardware store. Do not wrap your pipes with bath towels or newspaper!
• If you will be going away during cold weather, leave the heat on in your home, set to a temperature no lower than 55° F.