Today I learned how a septic tank works. So a septic tank is a system to manage waste when you aren't connected to a sewer treatment plant. The whole process works thanks to our friend gravity! As waste travels through the pipes in the home, it gets dumped into the first chamber of the septic tank. Typically a septic tank is a large concrete structure usually buried in the yard. Anaerobic bacteria in this chamber digest the waste and the solids (sludge) sink the bottom while the scum floats at the top, leaving a liquid in the middle full of nutrient chemicals! This substance is then filtered through the second chamber where aerobic bacteria break it down even more. This process creates gas (yup the smelly kind) which is vented out through pipes and the solid remains to be emptied out and the liquid goes through the drain field as it nourishes the green grass (so why exactly do we call it waste?)

I got to thinking about this after reading this post on the Good Blog:

On a related note, there is a good series that the discovery channel has on this topic, Filthy Cities: http://dsc.discovery.com/videos/filthy-cities-mass-sewage.html