Natural gas lines often run next to the plumbing pipes in your home. The gas comes into your home through an underground service pipe made of plastic or coated black iron and is piped directly to your gas appliances. Water heaters, clothes dryers, stoves and furnaces can all be gas fired. A slight gas odor may signal a leaky pipe joint. One quick way to search for the leak is to sponge a soapy solution over the pipe area that appears to be leaking. Bubbles will form at the sight, if there is a leak. You'll need to contact a plumber to make this repair. If you smell an unmistakably strong gas odor, do not check anything. Very likely, there is a potentially dangerous gas leak. Leave your house immediately and contact the gas or utility company.