How aerobic and advanced septic systems differ from a conventional tank, and the service contracts and checks Florida, Suffolk County and Arizona require.
By the SepticRated team · Facts checked against the sources listed below on November 1, 2026. General information, not professional advice.
In a conventional septic tank, solids settle, scum floats and the liquid runs out to the drainfield. An aerobic treatment unit (ATU) adds air. EPA describes it as a small-scale version of a municipal sewage treatment plant that injects oxygen to boost bacterial activity and nutrient treatment. Some units add pretreatment and disinfection stages. EPA says ATUs suit small lots, poor soils, high water tables and sites near sensitive surface water, and that regular maintenance should be expected for the life of the unit.
ATUs are one of several advanced designs. EPA also describes recirculating sand filters, where a pump sends effluent through a sand filter for a high level of nutrient treatment, and drip systems, which need a dose tank and electrical power. EPA notes extra upkeep for several of these designs: regular maintenance for the life of an ATU, periodic maintenance for mound systems, and added expense and maintenance for drip systems.
The newer rules target nitrogen. UF/IFAS says a conventional septic tank removes only about 30 percent of the nitrogen that flows into it.
Florida's rule for aerobic treatment units (Fla. Admin. Code 62-6.012, as amended effective June 21, 2022) puts the obligations in writing:
Advanced systems need a service provider for the long term, and Suffolk County's guidance tells owners that their service provider can inspect and maintain the system.
Suffolk County's guidance for I/A OWTS owners says the first three years of operation and maintenance are covered by the manufacturer's warranty, after which homeowners need to sign yearly maintenance contracts and pay for maintenance. Owners must register the system with the county Department of Health Services at final approval, with the registration updated every three years and when the property changes hands, at no cost.
In a homeowner fact sheet posted in 2017, the county describes a control panel with an electrical connection and high-water alarms, says systems run continuously or on demand depending on the design, and, based on manufacturers' information, puts the electricity cost of the provisionally approved systems at about $57 to $266 a year. Covers can be landscaped around but must stay fully accessible, and the control panel should be protected and easy for service providers to reach.
Arizona's rules put maintenance on the permit holder. Rule R18-9-A313 lists tasks that must be performed as applicable, including:
For aerobic systems under 3,000 gallons a day, the state general permit (R18-9-E315) also requires filters to be cleaned and replaced as necessary, and applicants submit the manufacturer's warranty and operation and maintenance recommendations. At sale, Arizona's transfer inspection applies. The rule requires the inspector to have a working knowledge of the type of facility being inspected, and the University of Arizona notes that not every inspector knows every system type, especially alternative systems, so ask about experience with yours.
Florida's rule makes a current contract with an approved maintenance entity a condition of approval, requires that entity to inspect the unit at least twice a year, and requires any business that services or repairs aerobic units to hold an annual permit from the Department.
Yes. Arizona's maintenance rule lists pumping accumulated residues among the tasks the permit holder must ensure are done, as applicable, and Suffolk County's guidance for I/A owners estimates that the average system needs pumping every three to five years.
In Suffolk County the I/A registration is updated when the property transfers. In Arizona the seller must hand over operation and maintenance documents with the inspection report. Elsewhere, ask your provider how the contract transfers.
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