If you’re installing a septic system—or living with one—it pays to learn the basics of how it works. This will help you take simple steps to prolong its life, understand what you should do if something goes wrong, and evaluate your options if you ever need to expand your system because of a home improvement project.

These one-house-at-a-time sewage treatment systems—used by one in five U.S. households and nearly half of all houses in the South—clean up wastewater just as well as city municipal systems. Septic systems are just better options for sparsely populated rural and spread-out suburban areas, where running sewer lines would be cost-prohibitive