Become a pro in all things aerobic systems
Aerobic septic systems use oxygen and disinfecting agents to clean wastewater.
They’re highly effective at sanitizing, making this system less likely to contaminate groundwater.
Aerobic systems are good for small homes and homes on high water tables.
Installing an aerobic septic system costs $10,000 to $20,000.
Aerobic septic systems are complex alternatives to conventional septic tanks. They are incredibly effective at cleaning wastewater with a multi-step process that separates the waste into layers, oxygenates it, and puts it through further disinfection. While they are expensive and may not be tenable for larger homes, they are ideal for homes near bodies of water and poor-quality soil. Here’s everything you need to know about aerobic septic systems.
There are many different types of septic systems that are considered either conventional or alternative. Aerobic septic systems are alternative septic systems that function similarly to municipal sewers, but on a very tiny scale. They share many of the same processes for treating wastewater, so aerobic septic systems produce much cleaner effluent than conventional septic systems.
The parts and setup of aerobic septic systems vary, but they usually contain the following components:
Trash tank
Aerobic treatment unit
Disinfectant chamber
Pump tank
Absorption field (also called leach field)
The trash tank functions similarly to a standard septic tank in a conventional system. Unlike a conventional septic tank, however, the trash tank separates the wastewater into three layers similarly to those gelatin desserts from the 1950s. The liquid effluent (wastewater) makes up the bulk of the contents with sludge at the bottom and scum floating on top, so it's marginally less bouncy than said gelatin abominations.
As the name implies, aerobic septic systems stand out from both conventional septic systems and other alternative types because of their oxygen usage. That liquid effluent pumps through a baffle into the aerobic treatment unit, where air is pumped in. But instead of donning leotards to 1980s tunes, aerobic bacteria feast on that oxygen-rich environment and attack the pathogens in the effluent.
Once the effluent finishes aerobic treatment, it flows to the disinfectant chamber. Disinfecting agents such as chlorine, bleach, or ultraviolet irradiation break down the last of the harmful germs before the effluent makes it to the pump tank. This can seem counterintuitive since it’s normally a bad idea to put bleach and other harsh chemicals in a septic tank. However, this is what makes an aerobic septic system different from the others. They need a disinfecting agent to work properly, just in a different component.
Pump tank construction varies, but more often than not, it has floats that determine when it's time to pump the effluent out. If enough effluent builds up, an alert goes off that it's time for maintenance.
After the alert, the effluent is sent to the leach field. It's usually sprayed out, and you can do this yourself, but you’ll need a local septic tank cleaner to periodically pump out the sludge in the trash tank.
Aerobic septic systems come in two varieties: one-tank and three-tank systems. One-tank systems have all the components in one tank, while three-tank systems house them separately.
Just like with choosing the right size for a conventional septic tank, choosing one- or three-tank systems depends on household size and expected water usage. One-tank systems work well for households of four to five people or less, assuming the home has five or fewer bedrooms. Homes with six or more bedrooms, or households with six or more members, would need a three-tank system.
If you’re wondering whether or not an aerobic septic system is the right choice for you, explore the pros and cons of the system below.
Aerobic septic systems don’t need as much maintenance as anaerobic systems. Conventional septic systems need frequent inspection and maintenance, even if they’re only pumped every three to five years. Aerobic systems still require maintenance, but they don’t produce as much sludge that needs to be pumped out.
They can be installed where conventional septic systems normally cannot. Homes on high water tables can’t install conventional septic systems because they run too much risk of poisoning the local water supply. Homes with poor-quality soil make conventional septic systems impossible because the absorption field is insufficient. Aerobic septic systems will work on poor soil because the wastewater is internally treated and then sprayed out.
They fit on small lots. Conventional septic tanks and their other parts need lots of outdoor space. If you want more of your yard back, or don’t have much yard to begin with, aerobic septic systems are very compact and easy to fit around trees, sheds, pools, and other elements that would normally cause safety issues with conventional septic systems.
They effectively sanitize water. While you still need to be mindful not to strain your system and pour harsh chemicals down the drain, the water you use is cleanly and effectively recycled. Detergents won't ruin your grass the way runoff in conventional septic systems might.
Aerobic septic systems cost far more than conventional. Anaerobic septic systems cost $3,000 to $8,000, but aerobic systems cost $10,000 to $20,000. One-tank systems cost significantly less than three-tank systems, but additional components, like bleach chlorinators, add to the installation expense.
They need electricity to function. The components in an aerobic septic system need power to keep your wastewater sanitized. This can compound their expensive aspects in terms of power bills and needing a backup generator if your power goes out.
Cold weather can slow them down. Your aerobic septic system might work slowly, or not all, if it’s too cold. Installing insulation is a workaround for this, but it makes these systems more expensive than conventional options.
You need to constantly refill it with chlorine tablets. Your state will have its own rules for how you need to disinfect your aerobic septic system. This can involve chlorine tablets every three to four weeks or a bleach chlorinator so that you can use liquid bleach, instead. While aerobic septic systems overall have less intense maintenance than conventional, they aren't as "set it and forget it" in this regard.
In conventional septic systems, wastewater flows to a leach field after it leaves the septic tank. This effluent is pulled down by gravity, where aerobic bacteria decontaminate it before it enters the groundwater. Aerobic septic systems use different components, more like a sewer, to produce more sanitary effluent. Subsequently, the leach field can be smaller than those used with septic tanks.
Yes, you’ll need to use bleach tablets unless you purchase a bleach chlorinator. If you install a bleach chlorinator in your aerobic septic system, you can use ordinary household bleach in liquid form. Chlorine tablets need to be designed for aerobic septic systems. The ones for pools cannot be used as they aren't strong enough to treat wastewater.
