Septic tank vs aerated treatment system: what is the difference?
Vermifiltration uses worms and other living organisms in a filter bed to break down household wastewater. An aerated system pumps air into the wastewater, helping bacteria consume the waste.
Both use natural biological processes. The difference is how they create the conditions for those organisms to work.
A worm-based system can be a good choice when low electricity use is a priority. An aerated system can suit properties that need a high level of treatment before wastewater reaches the land. But the particular model matters more than the label: worm-based systems have different treatment levels, and some use powered equipment too.
What happens inside a worm-based system?
Vermifiltration is a technical name for a living filter.
Wastewater passes through a bed that catches solid material while allowing liquid to drain through. Worms, bacteria and other organisms break down the waste held in the bed and help clean the water.
The worms live in a moist environment with access to air. They also move through the filter material, helping keep it open so water can pass through. They are doing much the same job they would in a compost heap, within a system designed to handle household wastewater.
WaterFlow’s NaturalFlow and BioPod systems both use worm-based treatment, but they work differently.
NaturalFlow’s treatment process does not need electricity. BioPod uses a small air pump to keep fresh air moving through its filter bed, along with a pump to move the treated water to the disposal field.
What happens inside an aerated system?
An aerated system also relies on living organisms, mainly bacteria.
Wastewater first enters a chamber where solids settle. It then moves into an aeration chamber, where a blower supplies air. The oxygen helps bacteria grow and break down more of the waste.
After this, another chamber lets remaining particles settle before the treated water is sent to the disposal field.
EconoTreat is WaterFlow’s aerated treatment range. It provides advanced secondary treatment, removing more of the remaining organic matter and suspended solids before the wastewater leaves the system.
Does aerated treatment always produce cleaner water?
You need to compare the treatment level of the actual models.
Within WaterFlow’s range, NaturalFlow has configurations offering different treatment levels, BioPod provides secondary treatment, and EconoTreat provides advanced secondary treatment. These are performance categories, rather than descriptions of how new or expensive a system is.
Some properties need additional treatment for a particular reason, such as reducing nitrogen. That is a separate question from simply asking whether a system uses worms or air.
EconoTreat offers nitrogen-reduction capability, with additional UV treatment available where specified. The proposed system needs to match what your property requires.
Which uses less electricity?
NaturalFlow has a power-free treatment process, making it worth considering if you are off-grid or want to keep electricity use down.
Whether the complete installation is power-free depends on where the house, tanks and disposal field sit. If wastewater cannot travel where it needs to go by gravity, a pump may still be required.
BioPod is a low-power option. Its small air pump supports the organisms in the filter bed, and its disposal pump moves the treated water out.
EconoTreat needs power for its blower and any pumps in the installation. That equipment supports the additional treatment taking place inside the system.
When comparing power use, ask about the whole setup, including the pumps needed for your particular site.
What maintenance will I be signing up for?
Both approaches need care. For either system, that includes being sensible about what goes down the drain and keeping the disposal field in good condition.
With a worm-based system, looking after the filter bed and its living organisms is central to keeping it working. Excessive fats, grease and harsh chemicals can cause problems. Any pumps and filters also need attention.
An aerated system needs checks on the blower, pumps, filters, alarms and treatment process. Sludge levels need monitoring too.
Ask for the maintenance schedule for the exact system being quoted. “Low maintenance” is more useful when someone explains what you will actually need to do.
Will either need a sucker truck?
NaturalFlow does not normally need routine septic pump-outs. Its organisms break down waste within the filter system, rather than relying on regular removal of accumulated septic sludge. It still needs appropriate care.
Aerated systems can accumulate sludge that eventually needs removing. EconoTreat’s owner’s manual gives an approximate pump-out interval of 3–5 years, with technicians checking sludge depth during servicing.
Regular servicing and pumping out are separate jobs, so check whether both are included in any running-cost estimate.
Will one take up less space in my garden?
There are two areas to think about: the treatment tanks and the disposal field.
BioPod has a compact treatment unit, which can help where installation space or access is limited. However, a small tank does not automatically mean a small disposal field.
Both worm-based and aerated systems still need to return treated water to suitable land. The treatment level can affect which disposal methods are available, but the ground must be able to absorb the amount of water your home produces.
Ask to see the proposed layout. That will tell you more about the impact on your garden than a photograph of the tank.
When would each be worth considering?
NaturalFlow is worth exploring when you want a power-free treatment process, particularly if the land allows gravity to move wastewater through the whole installation.
BioPod is worth exploring when you want worm-based secondary treatment in a compact unit and are comfortable with a small amount of powered equipment.
EconoTreat is worth exploring when advanced secondary treatment or specified nitrogen reduction is needed, and you have a reliable power supply.
These are starting points for a conversation. They do not restrict NaturalFlow to baches, BioPod to small homes or EconoTreat to large families. The system needs to be sized and configured for the household and the property.
How do I choose between them?
First, find out what treatment level your property needs. Then compare the options that can meet it.
From there, the useful differences are practical: electricity use, installation access, servicing, pump-outs and the space required for disposal.
At WaterFlow, we offer both worm-based and aerated systems. We can explain what each suitable option would look like on your property, what it would cost to install and what you would need to look after.
Get in touch with the team to talk through your plans.
Frequently asked questions
The main treatment process uses air and bacteria to break down waste. The word “aerated” refers to adding air.
No. NaturalFlow’s treatment process is power-free, but the site may still need a pump. BioPod uses a small air pump and a disposal pump.
Yes. Appropriately sized systems can handle wastewater from toilets, showers, kitchen and laundry. They are not just for toilet waste.
Some do. Aerated systems can still build up sludge. NaturalFlow works differently and does not normally need routine septic pump-outs. Always check the requirements for the particular system.
A power-free treatment process can reduce electricity costs. For a fair comparison, also include any disposal pumps, servicing, filter care and sludge removal that the particular system needs.
Start by checking the power demands of the complete installation. NaturalFlow is an option worth exploring because its treatment process needs no electricity. Powered systems need an off-grid supply capable of supporting their equipment reliably.
