Your septic system is a proper system. Many people just call it a septic tank, but it isn't just a tank. There is a lot more to it than that. If you are going to have a septic system at your house, then you should know more about it so that you know what's happening. Knowing what is happening in your tank will help you to understand why it needs to be pumped out periodically.
The tank can hold various amounts of fluid, depending on how big your house is and how much usage it will get. Inside the tank, there are two chambers. Each chamber has an outlet to the next part of the system that is higher than the inlet. That way, nothing moves through the system until it is ready.
The first chamber is full of anaerobic bacteria. They eat the solids that come in with your wastewater and create a sludge that falls to the bottom of the tank. As the bacteria consume all the incoming solids, the sludge will get higher and higher. This section may also have a greasy scum floating on top. As the water in this section gets cleaned, it moves to the next one.
There are often finer particles of solids left in the wastewater when it leaves the first chamber. The purpose of the second chamber is to let those particles fall to the bottom of the tank so that the only thing that leaves the tank is water. It will have a buildup on the bottom, just as the first section does, but it won't be quite the same stuff since most of it was handled in the first part of the tank.
The leech field is also called a drain field. It has outlets from the second part of the tank and runs through a series of pipes with tiny holes. The pipes are buried underground and embedded in gravel so the holes don't get blocked. As the water leaves the septic tank, it flows through those holes and filters into the ground to purify and rejoin the groundwater.
Knowing how your septic tank works can help you when there is a problem and you need someone to take care of it. For example, knowing that the sludge builds up lets you know you must have your tank pumped to get rid of that sludge. For more information on septic system pumping, contact a professional near you.