If you live in Central Florida, the water is part of your life. We boat on the Butler Chain of Lakes, we fish in Lake Toho, and we kayak in the crystal-clear springs of Wekiwa. The water is the reason we live here.
But recently, the water has been changing.
Residents who have lived on these shorelines for decades are noticing a disturbing trend. The clear water is Lake turning murky. Thick, neon-green mats of slime are choking the boat ramps. Fish kills—where thousands of silver bellies float to the surface overnight—are becoming more common.
We often blame “big sugar” or industrial runoff for these issues. While industrial pollution plays a role, environmental scientists are pointing a finger at a much closer, much quieter culprit: the backyard septic tank.
It turns out, your plumbing might be feeding the algae that is killing your view.
The Nitrogen Bomb
To understand why a septic tank—a device designed to treat waste—would hurt a lake, we have to look at the chemistry of what we flush.
Human waste is rich in nutrients, specifically Nitrogen and Phosphorus. In a functioning septic system, the tank separates the solids, and the liquid (effluent) flows into the drain field. The soil in the drain field acts as a filter. Bacteria in the dirt eat the pathogens (like E. coli) so that the water is safe by the time it reaches the groundwater.
However, standard septic systems are not designed to remove Nitrogen.
Nitrogen is dissolved in the water. It passes right through the tank, right through the gravel, and right through the sand. It enters the aquifer or the shallow groundwater flow that feeds into nearby lakes.
When this nitrogen-rich water hits a lake, it acts exactly like Miracle-Gro. Algae are essentially microscopic plants. When you feed them a steady diet of nitrogen (from urine) and phosphorus (from detergents), they explode.
This process is called Eutrophication. The algae bloom aggressively, covering the surface of the water. This blocks sunlight from reaching the seagrass below, killing it. When the algae eventually die and rot, the decomposition process sucks all the oxygen out of the water. The result? A “dead zone” where fish cannot survive.
The “Sand” Problem
Central Florida faces a unique geological challenge that makes this problem worse: our soil is essentially a beach.
In places with clay or loamy soil, water moves slowly. It hangs around in the “root zone” long enough for plants to absorb some of the nitrates. But in Orlando, the soil is extremely sandy. Water moves through it rapidly—sometimes too rapidly.
This “fast perk” rate is great for preventing puddles in your yard, but it is terrible for filtration. The nitrogen-loaded effluent races through the sand and hits the water table before the natural biology of the soil has a chance to treat it effectively.
Furthermore, Orlando has a very high water table. In some areas, the groundwater is only 12 to 24 inches below the surface during the rainy season. This means there is almost no separation between the “dirty” water leaving your drain field and the “clean” water moving toward the lake.
The Legacy of the 1970s
The issue is compounded by age. Thousands of homes in Orange and Seminole counties were built in the 1970s and 80s, long before we understood the impact of nitrate leaching.
These older systems are often just a concrete box and a few clay pipes. They have no advanced treatment capabilities. Many of them are failing, not in the sense that they are backing up into the house, but in the sense that they are no longer treating the effluent.
A “functioning” septic system (one that flushes) can still be a polluting one. A homeowner might think their system is fine because the toilet works, unaware that they are silently leaking pounds of nitrogen into the community lake every year.
The Regulatory Awakening: BMAPs
The state of Florida has realized that this is unsustainable. The Department of Environmental Protection (DEP) has begun implementing Basin Management Action Plans (BMAPs).
These are targeted strategies to reduce pollution in specific, vulnerable waterways, such as Wekiwa Springs or the Wekiva River Basin.
If you live in a BMAP zone (Primary Focus Area), the rules of the game are changing. You may no longer be allowed to simply repair an old, conventional septic system. If your system fails, or if you apply for a permit to add a bedroom or a pool, the state may require you to upgrade to an Enhanced Nutrient-Reducing (ENR) system.
The Technology of the Future
An ENR system looks different from the concrete box of the past. It essentially acts like a mini municipal treatment plant in your yard.
These systems use aeration (injecting oxygen into the tank) and recirculation methods to encourage the growth of specific bacteria that consume nitrogen. They convert the harmful nitrates into harmless nitrogen gas, which is released into the air.
While these systems are more expensive to install and require electricity to run, they are incredibly effective. They can reduce the nitrogen load leaving your property by 50% to 70%.
What Can Homeowners Do?
You don’t necessarily need to rip out your entire system tomorrow to help save the lake. Small behavioral changes can have a massive impact on the “Nutrient Load” you are generating.
- Skip the Garbage Disposal: Food waste is high in nutrients. When you grind up leftovers and send them to the septic tank, you are adding a massive load of nitrogen and biological oxygen demand (BOD) to the system. Compost it instead.
- Fertilize Responsibly: Often, the green ring around a lake isn’t just from septic tanks; it’s from lawn fertilizer washing off the grass. Use slow-release nitrogen fertilizer and keep it at least 10 feet away from the water’s edge.
- Inspect Regularly: A leaking tank or a crushed drain line concentrates the pollution in one spot. Regular inspections ensure the system is distributing the effluent evenly, giving the soil a fighting chance to filter it.
Conclusion
The lakes of Central Florida are our shared backyard. They are the playground for our children and the habitat for our wildlife. But they are fragile. The clarity of the water is directly linked to the health of the infrastructure buried in the yards that surround it.
The transition from “disposal” to “treatment” is the next great shift in homeownership. It requires viewing our plumbing not just as a convenience, but as a responsibility. Whether it involves upgrading to a nitrogen-reducing system or simply changing what we flush, protecting the water starts with understanding that the drain in our bathroom is connected to the view from our porch. For those concerned about their impact or living in a sensitive BMAP zone, consulting with a knowledgeable septic company Orlando residents trust is the first step toward turning the tide against the green slime and reclaiming the blue.