While it sounds a bit disturbing, older septic systems are actually called "cesspools." They are made of concrete blocks or flat fieldstone cylinders with holes in the sidewalls.
Did you know that baffles in your septic tank are imperative to proper function? Healthy septic baffles are instrumental in preventing sewer blockages and keeping solid waste material from entering the sensitive leaching system.
Did you know that you should never build or pave over a drain-field? Your drain field plays a large part in decomposing waste after it has passed through your tank and needs to be left unobstructed to filter the waste water properly.
Wonder why septic tanks need to be cleaned periodically, even when sewage is handled efficiently in the leaching bed? Waste always contains at least a little indigestible material that creates a layer of sludge on the bottom of the tank over time. If not removed, that layer can grow -- and grow -- eventually blocking the system.
If you're just learning about septic systems, it's easy to conclude that the tank is where the action is. That's not quite true, though. Where the tank is necessary for storing and sorting waste, the leach or drain field is where most of the waste treatment takes place.
Soil absorption pits, also known as "beehives," are similar to cesspools but have a regular tank that runs from the house into a pit in the ground.