There's bacteria everywhere — including your pipes and septic system. Add in biofilm (that "slimy goo" composed of bacteria and bacteria byproducts) and things get real.

Now contemplate what goes down your drains each day:

Over time, these add up and gunk up — creating a breeding ground for bacteria and odors.

That P-shaped piece of pipe located under your sink (and in other fixtures behind walls) holds a specific amount of water that blocks sewer odors and gases from seeping out your drains.

Plumbing that isn't used often — like a guest bathroom toilet or shower — is susceptible to that helpful water drying up. When it does, the stench and gases from the sewer can seep right into your home.

Ever wondered where the gas and odors go? (Let's leave Cousin Ralph out of this.) Vent pipes are designed to vent these away, and they're connected like a small network to your drain pipes.

If you didn't have vent pipes, you wouldn't want to be in your house for very long. A similar situation happens if one of your vent pipes gets clogged — the stench is going to make an entry.

Food trapped in your garbage disposal can reek beyond description. Forgetting to run the disposal means the organic scraps you pushed in there are doing their decomposition dance right under your nose.

It's all natural, but it still smells horrid — and could be the culprit of your stinky situation.

A breach is any hole or crack that can stem from tree roots, clogs causing pressure, or the line splitting as it moves and settles underground. When this happens, it may lead to a sewage leak.

Anytime there's leaking sewage, there will be a strong, awful odor. You'll smell it indoors and outdoors — your neighbors may even smell it.