Palmetto Bay homeowners who replace a septic system face $10,000 to $20,000 in added costs under state and county rules requiring upgraded equipment.

The village published a guidance page outlining how House Bill 1379 and Miami-Dade County Ordinance 22-83 affect residents in Basin Management Action Plan (BMAP) areas. Miami-Dade is one of 57 Florida counties covered by the state law.

The bottom line: homeowners on lots of one acre or less who need a new septic system must either connect to central sewer, if available, or install an enhanced nutrient-reducing onsite sewage treatment and disposal system. Conventional septic tanks no longer meet the standard for new or replacement installations in BMAP areas.

What changed and when

HB 1379, signed by the governor on May 30, 2023, took effect July 1, 2023. It requires nitrogen-reducing systems in all BMAP areas, according to the Florida Department of Environmental Protection. The systems must achieve at least 65 percent nitrogen reduction.

Separately, the Miami-Dade Board of County Commissioners adopted Ordinance 22-83 on July 7, 2022, with requirements taking effect Jan. 1, 2023. That ordinance created four tiers of septic system standards, ranging from conventional (Type 1) to the most stringent (Type 4), which meets Florida Keys-level effluent limits. Commissioner Rebeca Sosa was the prime sponsor.

Most properties will need a Type 2 or Type 3 system, according to the ordinance. Properties closest to water bodies or within a drinking water wellfield will need Type 4.

What it costs

The county estimates the price difference between a conventional septic system and a performance-based replacement at $10,000 to $20,000, depending on site-specific factors, according to the Ordinance 22-83 analysis.

The rules are not retroactive. They apply only when a homeowner installs a new system or replaces an entire existing one, including both the tank and the drainfield. Repairs short of a full replacement do not trigger the upgrade.

State funding dried up

Homeowners looking for financial help face a gap. The state's Septic Upgrade Incentive Program is no longer accepting new applications because funding has been exhausted, according to the village's guidance page. The program will continue processing invoices for work already authorized.

The Florida Department of Environmental Protection is working with nine counties to set up county-specific incentive programs, but Miami-Dade is not among them. The listed counties are Citrus, Hernando, Leon, Marion, Orange, Pasco, Seminole, Volusia and Wakulla.

Why it matters locally

About 110,000 properties across Miami-Dade County use conventional septic systems, according to the county's ordinance background. Conventional drainfields typically sit six to 24 inches above the Biscayne Aquifer, the county's primary drinking water source, which connects to Biscayne Bay.

The county's Biscayne Bay Task Force recommended expanding sewer infrastructure and strengthening septic standards. Full sewer buildout would cost roughly $4 billion and take years, according to the ordinance analysis. Upgraded septic systems serve as a parallel strategy.

What homeowners should do

The village's guidance page lists seven Florida-approved nitrogen-reducing aerobic treatment units certified under NSF Standard 245, from manufacturers including Delta Treatment Systems, Fuji Clean USA and Hoot Systems. The approved units range from 55 percent to 85 percent nitrogen reduction.

Residents with questions can contact the Miami-Dade Department of Environmental Resources Management Water and Wastewater Section at 305-372-6789.