Conventional vs. Advanced Septic Systems

The conventional system

A conventional septic system is the one most people picture: a septic tank followed by a gravity-fed leaching bed. Where a property has enough suitable soil and space, it's a proven, straightforward approach — fewer moving parts, and the soil does the finishing treatment.

The advanced system

An advanced system adds a treatment unit — and sometimes pumps and controls — to treat the effluent to a higher standard before it's dispersed. That higher level of treatment is what makes difficult sites workable and can shrink the footprint the dispersal area needs.

What pushes a property toward advanced

• A small or oddly shaped lot with no room for a full conventional bed
• Poor or slow-draining soils
• A high water table or wet site
• A high daily design flow, such as a large home or commercial building
• Setbacks from wells, watercourses or property lines that limit usable area

The trade-off

Advanced systems have more components — treatment units, sometimes pumps, alarms and controls — so they generally cost more than a straightforward conventional system and have a bit more to maintain. In return, they can make a lot buildable that otherwise wouldn't be, or reduce how much land the system ties up. It's a trade-off, not a ranking.

How you actually decide

You don't choose the system from a brochure — the site chooses it. A proper site evaluation and design tell you whether a conventional bed will serve the property or whether an advanced approach is the better (or only) fit. That's the step that turns the question into a clear answer.