Because certain components of your plumbing, like the pipes, don't have any moving parts, a lot of people assume that once the plumbing is installed, there's nothing else to worry about. This stuff will take care itself because it doesn't have to do much other than sit there.
But just because pipes don't have cogs, gears, and motors, doesn't mean that they are indestructible. The constant movement of water and other substances through pipes can eventually take their toll, and if you smell something coming from your plumbing, you have a problem you shouldn't ignore.
Fortunately, you don't have to, as some quick, easy fixes exist for some of these issues.
The Sewage Line Is The Source Of The Odor
This problem has a lot more unknowns. If a vent is blocked, this could be a simple matter of clearing out some leaves, and the problem is solved.
If it's further down the line, such as a breach in your sewage pipe, it's unlikely you can solve this yourself.
Try conducting an inspection by yourself first. Look at all the accessible areas of plumbing to see if you can find anything.
If you can't, and the smell persists, now is the time to call a professional who has the right tools and know-how.
Water Is the Source of the Odor
Tracking down the source is an important first step, and if you're getting the smell every time you turn on the tap, the source is coming from your water. However, that doesn't automatically mean that problem is from your water source, and that it's bad water being pumped into your house.
It's possible that your issue is coming from your water heater tank if you have one. If the water heater temperature is too low, it creates a perfect habitat for bacteria that prefers dark, moist, warm places. A protected water tank can fit that bill.
The fix for this is very simple. Just readjust the temperature of your water heater, raising to somewhere in the neighborhood of 135-140°F. That's too hot for most bacteria to survive in.
This is one tip that any plumber will ask you to try first rather than getting a professional response, because the solution you use here will be the same one a plumber uses.
The Drain Is the Source of the Odor
Just pour water down your drain. That's it. A smell coming from just one drain is the result of an empty p-trap.
Your p-trap is the bend in the pipe that's just under your sink, and it's designed to hold a certain amount of water.
That water acts like a super cheap, super efficient "vapor barrier," that prevents sewer gas from entering your home. Pour more water in and you're done.