How a Septic Tank Works
When buying a rural property that isn't connected to the city's sewerage system, or if you have a large property already and you want to add bathroom facilities to the outskirts of the lot without running plumbing pipes to that area, a septic tank may be what you need. This type of system isn't connected to the city's sewers, and it can be added on just about any plot of land. If you know that your property needs a septic tank, note a few basics about how these systems work, so you know if it's the right decision for your plumbing needs, and know how to maintain it over time.
The tank
A septic tank will be buried some distance away from your home, or the area of your land where you have toilets and sinks installed. Pipes will connect the toilets and sinks to this tank.
A septic tank is not just any metal or plastic tank. It will be solid and resistant to corrosion, so it doesn't leak. It will also have an opening at the top so it can be accessed as needed.
Inside the tank, there will be bacteria added. It works to break down waste as it enters the tank. As that waste breaks down, a sludge is formed, and this sludge sinks to the bottom of the tank. Above this sludge is watery waste, referred to as effluent.
Filters and drain field
If you're not familiar with a septic system, you may assume the tank simply holds waste until it is emptied, like an outhouse. This is not correct, as a septic tank is then connected by pipes to what is called a drain field. The effluent in the tank is filtered and then flows through the pipes that connect the tank to the drain field. These filters help to keep solid waste out of the drain field, and also help that solid waste to break down even further.
Note that a drain field isn't just a big hole or area of the ground where a pipe simply empties; instead, drain field pipes will usually have holes along their bottom. There is also typically a sand filter system under the drain field pipes. This allows the effluent to drain along a larger area than having it simply dumped into a pit or small space of your property behind the septic tank. That larger drain field then absorbs the effluent into its soil, leaving behind just the sludge in the tank that is cleaned and emptied as needed.