A septic tank, at its most basic level, is a concrete cube that holds wastewater from your plumbing system. Solid materials eventually float to the bottom to create sludge, while floatable matter like oils float to the top as scum. Wastewater is slowly released from the septic tank into a drain field where it is filtered through soil, sand and other organic matter to naturally neutralise and purify it before it is released into the groundwater.
Choosing a quality, well-built septic tank is highly important. If your tank becomes damaged, it could lead to plumbing backups or even sewage leaking into your yard. You should also ensure that your tank is large enough to accommodate your home. The size you choose will largely depend on the number of bathrooms and how many people inhabit the home.