Septic Guides · Florida

Aerobic (ATU) vs. Conventional Systems

Most Manatee County homes run conventional gravity systems. But a meaningful share — high-water-table lots, environmentally sensitive parcels, many Lakewood Ranch-area estates — carry aerobic treatment units instead, and ATU ownership comes with obligations conventional owners never think about.

How they differ

A conventional system is passive: the tank separates, the drain field's soil finishes treatment, and nothing has a power cord. An ATU is an active mini treatment plant — an air pump feeds oxygen to aerobic bacteria that treat wastewater to a higher standard before discharge, which is why regulators allow ATUs where conventional fields won't fit the site conditions.

What Florida requires of ATU owners

• An operating permit — ATUs are in the category Florida requires ongoing permits for, along with performance-based and commercial systems
• A maintenance contract with periodic professional inspections — not optional, and the obligation transfers with the deed when a home sells
• Electricity, always: an ATU without power is a conventional tank without a proper drain field, which is to say, a problem

Tanks, materials and brand names

• Concrete tanks dominate here for good reason — weight resists buoyancy in our high water table (see the flooding guide for why that matters), and modern concrete lasts decades.
• Polyethylene tanks shine on tight-access lots where a crane can't reach, at the cost of needing careful anchoring in wet ground.
• Chambered drain fields (Infiltrator-style plastic chambers) have largely replaced gravel-and-pipe in new construction — faster installs and strong performance in sand.
• ATU brands like Norweco and similar units each carry manufacturer-specific service points — your maintenance provider should know yours by name.

Frequently asked questions