Many people are far too generous with their house keys, never thinking that this might come back to harm them. Perhaps you give copies of the key to your house sitter, to your best friends, and of course, to your roommates and their significant others. But what happens when these keys get into the wrong hands?
When a roommate moves out, the standard advice is to change the locks, but very few people actually do this. Even if the roommate left on good terms, you have no way of knowing who now has access to your home. Perhaps she's given a key to an old boyfriend, or to some of her friends. Do you want them showing up in your home unannounced? Even if you think this could never happen to you, the truth is that you never know where these keys end up once they've left your hands.
If your house key is marked "Do Not Duplicate," as many are, you may assume that you know exactly who has a key. While it is more difficult to get a copy of these keys, it is certainly not impossible. Although locksmiths have the right to deny anyone a copy of this key, a less scrupulous professional may copy these keys without hardly a thought to the reason behind this marking. Making a copy of these keys is not nearly as hard as you might expect; just because it's marked "do not duplicate" doesn't mean that there aren't copies of it out there.
There are other ways for your key to get into the wrong hands than giving it away. What happens when your purse is stolen, with your keys inside? The thief has your drivers license, with your address, as well as your keyring with your house key. This is an immediate sign that you need to change the locks, lest this thief break in to your home by walking straight through the front door. Anytime your house key goes missing, especially if other identifying information has been taken as well, it is a sure sign that your door locks are no longer secure.
Finally, another threat to the safety of your house key comes in the form of the ubiquitous "hide-a-key." While this is certainly a useful device when used appropriately, far too many people use this as an excuse to leave their key basically out in the open. For example, using a hide-a-key shaped like a rock, and then setting it on your deck with no other rocks in sight, is not going to fool anyone. Worse yet are those who keep their spare key under a flower pot or door mat, or resting on top of the door frame. These are the first three places any thief will look for a key! If you are going to hide a key outdoors, use a hide-a-key, and arrange it so that the object looks like it belongs there.
What does all of this mean for the safety of your home? Above all, you must be conscious of exactly where all copies your house keys are. If in doubt, change the locks! This may be a hassle, but it's far better than coming home to find out that a thief has broken in by simply unlocking the front door.