Glossary

Absorption Field: The area where treated wastewater is released into soil for final filtration. Also called a drainfield. In Florida the water table is usually what determines how it can be built.

ATU (Aerobic Treatment Unit): A system that introduces air so aerobic bacteria treat the wastewater. NSF 245-certified ATUs are one of three technologies Florida accepts for meeting nitrogen-reduction requirements.

Baffle: A barrier inside the tank that controls flow between compartments and keeps solids from reaching the drainfield. A failed baffle often produces symptoms that look like drainfield failure.

BMAP (Basin Management Action Plan): A state restoration plan for a waterbody that already fails water quality standards. If your property sits inside one, nitrogen-reducing requirements may apply — and BMAP boundaries follow watersheds, not county lines.

Chapter 62-6, F.A.C.: The Florida Administrative Code chapter governing onsite sewage treatment and disposal systems. It moved from the Department of Health to the Department of Environmental Protection as part of the 2021 transfer of authority.

DEP (Department of Environmental Protection): The state agency that has held statutory authority over onsite sewage since July 1, 2021. Seventeen counties now permit directly through DEP; the rest still go through county health departments.

Effluent: The liquid leaving the septic tank after solids settle out. Its quality determines how much treatment the soil still has to perform before the water reaches groundwater.

ENR-OSTDS: An Enhanced Nutrient-Reducing Onsite Sewage Treatment and Disposal System — one that removes at least 65 percent of total nitrogen, versus roughly 25 to 30 percent for a conventional tank. Required in designated areas under HB 1379.

Form DEP4015: The state application form used for septic permits in Florida. The same form is used whether you apply through DEP or your county health department — only the submission destination differs.

HB 1379: The 2023 law (Laws of Florida 2023-169) that expanded where nitrogen-reducing systems are mandatory and created the Indian River Lagoon Protection Program.

INRB (In-Ground Nitrogen-Reducing Biofilter): A layered media bed that treats effluent as it passes through. Generally the least expensive of Florida's three approved nitrogen-reducing technologies.

Indian River Lagoon Protection Program: A program created by HB 1379 covering parts of Brevard, Indian River, St. Lucie and Volusia counties. It carries Florida's strictest septic rules, including a requirement that existing systems be sewered or upgraded by July 1, 2030.

Karst: Limestone geology that dissolves over time, creating voids, conduits and sinkholes. The corridor through Pasco, Hernando, Citrus and parts of Marion can require geotechnical assessment before a septic installation.

Mound System: A drainfield built above natural grade. Common across South Florida and coastal areas where the seasonal high water table sits within 24 inches of the surface, leaving too little unsaturated soil for treatment.

OSTDS: Onsite Sewage Treatment and Disposal System — Florida's formal regulatory term for what most homeowners call a septic system.

PBTS (Performance-Based Treatment System): An engineered system certified to meet a specific treatment target. Nitrogen-reducing PBTS models on Florida's approved list are one route to meeting the 65 percent standard.

PFA (Priority Focus Area): The part of a BMAP where groundwater is most vulnerable and requirements are strictest. Whether your parcel falls inside one determines both whether nitrogen rules apply and whether upgrade grant money is available.

Private Provider Inspection: Since July 1, 2022, Florida has allowed owners or authorized contractors to hire a private provider for certain OSTDS inspections instead of waiting on the permitting office.

Riser: An extension bringing a buried tank lid to ground level. Costs $200 to $400 and typically pays for itself in two pump-outs by eliminating the charge to locate and dig out lids.

Seasonal High Water Table: The highest level groundwater reaches during the wet season. It is the dominant constraint on Florida drainfield design — where it sits within 24 inches of the surface, a conventional in-ground field usually cannot be permitted.

Section 381.0065, F.S.: The Florida statute governing septic systems. Among other things, it prohibits homeowners from installing their own systems — work must be done by a state-registered or Master Septic Tank Contractor.

Site Evaluation: An assessment of soil, topography and water table that determines what a property can support. In Florida you may have the permitting authority perform it or hire a qualified private site evaluator.

SUIP (Septic Upgrade Incentive Program): A state program that paid up to $10,000 toward upgrading an existing conventional system to nitrogen-reducing, in designated Priority Focus Areas. DEP has closed it to new applications because its funding is exhausted; the county-run programs built on it continue, and Volusia and Brevard pay more than the old state ceiling. Eligibility is usually based on location rather than income.