In Disney/Pixar's "Finding Nemo," a fish says that all drains lead to the ocean, and Nemo escapes a dentist's office by jumping down the drain. Could a fish really get to the ocean this way?

We're sorry to say that in real life, Nemo wouldn't have made it. And even though all water on earth returns to the ocean eventually, pipes don't usually lead there directly.

So what would actually happen? Well, it wouldn't be pretty.

Whenever you flush a toilet, wash a dish or take a shower, the water you use becomes sewage -- in other words, it becomes unclean water. You can't dump sewage right outside a house, into an ocean or into a river. It stinks and it carries dangerous bacteria and chemicals. In order to safely dump the water, you have to remove all the "junk" mixed in with it.

There are two ways we do this. Some houses have a cleaning system called a septic tank buried in the backyard. Most houses and apartments in big cities send sewage to one large wastewater treatment plant. In "Finding Nemo," Nemo is in a big city, so the sewage would have gone to a wastewater treatment plant to be cleaned.

First, Nemo would tumble down twisting pipes (1) leading to a pipe called the sewer main (2). Nemo and all the sewage from the area would travel through a series of pipes leading to the wastewater treatment plant (3). A fish probably wouldn't survive this part of the journey, because the sewage would be toxic. Also, Nemo is actually a saltwater fish, so he wouldn't last long even in clean freshwater. But let's say he did manage to make it to the wastewater plant. Then what?

Most plants use pumps to get the sewage to the wastewater treatment area. In order to keep big pieces of junk from clogging up the pumps, the pump machinery passes the sewage through rotating blades (4). The blades break big chunks of stuff into smaller chunks. There's little chance Nemo would get past that.

If the plant didn't have pumps or rotating blades, Nemo would have gone directly to several large pools (5). In each pool, the heavy junk in the water would gradually sink to a sludge layer, and the lighter junk would rise to a scum layer. This process cleans a lot of the junk out of the middle layer of water.

This cleaner water would then flow to tanks filled with chlorine (6). The chlorine's job is to kill the remaining bacteria in the water and counteract any dangerous chemicals. And if Nemo had somehow made it this far, the chlorine would probably do him in, too.