Turn Off the Main Water Supply: Closing the valve on the main supply line cuts off water to the house but still allows outside sprinklers to work. If you do spring a leak inside, the line will be under some initial pressure, but it will not continue to spray water. There is no downside whatsoever [to turning off the water]. It takes a little bit of time, and it can save thousands of dollars in potential damage.
Check the Sump Pump: If your sump pump fails while you’re gone and a major storm comes around, you could return to a flooded basement, so make sure the sump pump is working before you leave town.
Turn Up the Thermostat—But Don’t Turn Off the A/C Unit: If you have a programmable thermostat, set and hold the temperature to have the house at 85 degrees while you’re gone (in the summer), then the day before you get back, get it down to 72. If you have a manual thermostat, it’s still worth turning it up while you’re gone to avoid wasting energy. You’ll just have to deal with a hot house when you get back.
Don’t turn off the air conditioner or furnace during your vacation. It’s important to keep the temperature from climbing too high to avoid heat buildup, which can have an effect on surfaces like wood floors.
The same goes for winter travelers, but in reverse. Turn down the thermostat while you’re away for the holidays, but don’t turn off the furnace completely, which could put your pipes in danger of freezing.
Keep Flowers Alive With a Soaker Hose: If you’ll be gone for several days and don’t have an in-ground sprinkler system (or a neighbor kid who can water your garden), use a soaker hose to keep the flowers or veggies watered. You can to set up your hoses on a timer to turn them on and off at preset times.
Unplug Electronics: Unplugging electronics or turning off the surge protector can save you money as well as protect your home in the event of a power surge while you’re away.
Light Rooms With Timers: This makes your house appear occupied while you’re gone and a less appealing target for burglars. Timers are available at home centers for less than $10 a piece.
Add Antifreeze to the Toilet: One for winter travelers — As noted previously, you’ll want to turn off the water to the house before you depart. If you’re traveling in wintertime, flush the toilets to drain the water in the tanks. That way, in case your furnace stops working, the water in the tanks won’t freeze, expand, and crack the porcelain. But even if you flush the toilet after you shut off the water supply, you’ll still end up with some water in the toilet bowl. Pour a little antifreeze into the toilet to keep it from freezing. *Be sure to use marine antifreeze, which is nontoxic.