Solutions for Biscayne Bay: Septic Tanks

Septic Tanks

Septic tanks are a form of on-site wastewater treatment widespread throughout South Florida. Many were installed in places without sewer lines as temporary wastewater treatment solutions until municipal wastewater services could be built but in most areas, that never happened. Even when working properly, this sewage treatment method is ill-suited for South Florida due to the region’s unique geological characteristics. The porous limestone geology and shallow water tables do not offer sufficient dry ground for proper cleansing and filtration of waste before it enters Biscayne Bay, tributary canals, and our drinking water aquifer. This problem is further exacerbated by rising sea levels, as over half of the 120,000 septic tanks in Miami-Dade County experience inundation by the rising water table at some point during the year.

Septic tanks represent a significant source of pollution, particularly in the northern areas of Biscayne Bay, where over half of the septic tanks are concentrated. Despite federal directives dating back to 1970, which advised Miami-Dade County to discontinue the use of septic tanks, the County still heavily relies on septic systems and continues to permit the installation of new tanks. Furthermore, a comprehensive registry of all tanks nor a maintenance requirement for existing tanks does not exist. Although a 1970 County ordinance mandates hookups to sewer lines, this law has been largely unenforced. 

Flooded septic tank


  • Phase Out Septic Tanks: Advocate for a comprehensive plan to phase out septic tanks in Miami-Dade County and transition to centralized wastewater treatment systems wherever feasible.
  • Infrastructure Investment: Secure government funding and support for the expansion and improvement of sewer infrastructure to facilitate the transition away from septic tanks.
  • Monitoring and Regulation: Push for stronger regulations and monitoring of septic tanks, including regular inspections, maintenance requirements, and mandatory upgrades or replacements when necessary.
  • Education and Outreach: Develop educational programs and outreach campaigns to inform residents about the environmental and health impacts of septic tanks.
  • Environmental Protection: Work to protect sensitive ecosystems, such as Biscayne Bay and the Biscayne Aquifer, from contamination resulting from septic tank discharges.
  • Sea Level Rise Mitigation: Advocate for measures to mitigate the impact of sea level rise on septic tanks, including raising tanks, improving coastal defenses, or relocating vulnerable systems.


  • Immediate Connection to Sewer Main: Require property owners with septic tanks located adjacent to sewer mains to connect to the sewer system promptly, prioritizing the elimination of septic systems in areas where sewer infrastructure is readily available.
  • Maintenance Requirements: Implement mandatory maintenance requirements for septic tanks, including regular inspections and pumping, to prevent malfunctions and contamination.
  • Ban New Installations in Flood-Prone Areas: Halt the permitting of new septic tank installations, particularly in areas prone to flooding or vulnerable to sea level rise.
  • Invest in Sewer Infrastructure: Allocate funding and resources to expand sewer infrastructure in areas currently reliant on septic tanks and promote the benefits of transitioning to sewer systems.
  • Public Awareness Campaigns: Launch public awareness campaigns to educate the community about the risks associated with septic tanks and promote the benefits of transitioning to sewer systems.
  • Climate Adaptation Planning: Develop and implement climate adaptation plans that specifically address the challenges posed by septic tanks in the context of sea level rise and changing environmental conditions. This plan should inform a septic-to-sewer conversion strategic plan.
  • Septic Disclosure Ordinance: Educate realtors and the public on the County’s existing septic disclosure ordinance.


  • The National Wildlife Federation – Clean Water State Revolving Fund: The largest source of federal funding for clean water infrastructure projects, including green infrastructure. This federal-state partnership provides grants to states, and states use this funding to make low-interest loans to communities for wastewater and stormwater infrastructure projects.


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