Photograph of excavator machine digging the ground for septic tank installation.

Gravity Systems vs. Dosing Tanks and Why it Matters to Floridians

Septic systems are a vital part of Florida’s infrastructure. This means that dramatic variations in the seasonal water table make it so that homeowners and septic system providers should know the equipment required to achieve optimal compliance. One important consideration is whether your property needs a dosing tank. Here we will explain the history of septic systems in Florida and why dosing tanks can be valuable to your home.

Graphic with a sand colored beige background and a large green quotation mark symbol and underneath that is large dark blue text that reads "Many Floridians are incorporating dosing tanks, not because they're required, but because they also help the environment."

What is a Septic System? 

A septic system is a self-contained, on-site wastewater treatment system. Septic systems get used in homes, businesses, restaurants, and other buildings that aren’t connected to a central sewer system. 

Wastewater from toilets, showers, sinks, and laundry gets collected in a septic tank. The septic tank allows solids to settle to the bottom of the tank while storing effluent, also known as grey water until it discharges into a drain field for further treatment.

What is a Gravity Septic System?

As the name suggests, a gravity system uses gravity to move effluent from the septic tank to the drain field. This type of system is often preferred because there is no need for pumps or other mechanical components. Gravity systems are also less expensive to install and maintain than most other types of septic systems.

The process is simple. Gravity forces the effluent into perforated pipes in the ground. As the liquid seeps downward, it’s naturally purified by the gravel and soil until it eventually reaches groundwater. 

Advantages of Gravity Systems 

  • Familiarity: Gravity systems are prevalent. 
  • Natural: Gravity systems rely on natural processes for treatment to be more environmentally friendly than other types of septic systems.

There are a few disadvantages to this system. Gravity tanks function best on sloped terrain, though it does not have to be sloped. Many homes’ landscapes in Florida do not have ideal gravity naturally, so professionals like ACE help maintain the slope of the pipes. 

You can still maintain the flexibility to decide where you want your drainfield. Say, for example, you want to place your drainfield in the back of the house, but the lack of gravity would require you to pump the effluent.

What is a Dosing Tank?

A dosing tank is an add-on to the septic system that uses pumps to move the effluent to the drain field—this system gets used when the drain field sits above the tank, which neutralizes gravity.

Dosing tanks are an additional expense on top of the septic tank. Still, they are often required if you’re dealing with difficult soil conditions or a situation in which gravity will not move the wastewater into the drain field.

Here’s how they work. Solids settle to the bottom while the effluent flows from the septic tank into the dosing tank. Then, a float activates the pump, which sends the wastewater to the drain field. The pump runs until fluid reaches a set level determined by your contractor. This process repeats each time effluent levels reach the float operation level. 

The pump will run continuously if the tank is consistently full and can overheat, burn out, or break down. That’s why it’s essential to have a dosing tank that is the right size for your home.

A high water alarm will sound audibly and visually if the tank is holding too much effluent. This alarm is not located in your home. It is usually located outside, on a pole, near the dosing tank. Otherwise, it can be mounted on a wall on the home’s exterior.  

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Why Florida?

Septic systems in Florida often require dosing tanks. The timeline with which this became a reality has also forced Florida homeowners to be diligent about their understanding of dosing tanks and their role in keeping the Florida aqueduct sanitary. 

For reference, homes built before 1972 required a 6-inch separation between the drain field and the water table.

Homes built between 1972-1995 required a 12-inch separation between the drain field and the water table.

Lastly, homes built from 1995 to now require a 24-inch separation between the drain field and the water table.

So, what does this mean exactly? For every inch of separation required between the drain field and the water table, a homeowner must consider the necessary equipment to be compliant. Many homes in Florida have drain fields that sit higher than the tank, and because the Florida water table has such a varying spectrum, a dosing tank may be your only option.

Let’s use some basic math to demonstrate our point.

If the water table in summer is only 10 inches high but can reach as high as 50 inches in winter, then you need to construct your septic system based on the seasonal high. Remember that the most recent legislation states that a 24-inch separation must be maintained between the bottom of the drainfield and the seasonal water table. With these elevations, a dosing tank with a pump would be required. Namely, to help pump wastewater into the drain field when gravity can’t do it by itself.

An ACE inspection can reveal whether or not a dosing tank is required or recommended. After all, a dosing tank helps keep the septic system from backing up, leading to the prolonged life of one of the most critical elements of your home or business.

Many Floridians are incorporating dosing tanks, not because they’re required, but because they also help the environment. Fewer septic emergencies mean less environmental impact. So, between legislative parameters, septic system maintenance, and environmental considerations – dosing tanks are often a no-brainer for homeowners that can afford them. More on that later.

Advantages of Dosing Tanks:

There are several advantages of dosing tanks, including:

  • Versatility: Dosing tanks can be installed in almost any location. This provides flexibility in determining the location of your drainfield. If all setbacks are maintained, you could have your drainfield at the back of your property, if desired.
  • Environmentally Friendly: Dosing tanks don’t stress the soil much because the wastewater gets discharged slowly and evenly. This promotes a more natural filtration through the soil.

Disadvantages of Dosing Tanks:

While dosing tanks have many advantages, they also have certain disadvantages:

  • Cost: Dosing tanks are definitely not cheap.
  • Additional Maintenance: Dosing tanks require electrical components, which must be wired and maintained. 

Cost of a Dosing Tank

Remember that for many Floridians, a dosing tank is not just a “nice-to-have” but a must-have. Knowing this will soften the reality that a dosing tank can run anywhere from $2,400 – $3,000. When this gets added on top of a septic system installation or large-scale maintenance project, the price can quickly exceed $8,000.

However, a properly running, reliable septic system is an investment worth paying for. After all, your home is your greatest asset, and when it comes time to sell that asset, a septic check will be required. Making this investment now will help maintain your home’s value and preserve the life of your septic system.

If you’re considering a dosing tank for your Florida home, or want a consultation on a new build, contact ACE Septic & Waste today. We provide installation, maintenance, repair, and inspections to the greater Tampa Bay area and surrounding counties. Call us at (727) 455-5885 to learn more about our services or schedule an appointment. Our team of experts can help you decide if a dosing tank is suitable for your home.

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