The main types of septic systems include conventional septic systems, chamber systems, mound systems, aerobic treatment units (ATUs), sand filter systems, advanced treatment systems, and holding tanks.
The right septic system depends on several factors, including soil conditions, lot size, drainage, groundwater levels, property layout, and household water use. While some homes can use a traditional septic system, others may require engineered or advanced solutions as part of septic system installation.
In this guide, we’ll explain how each septic system works, where it is commonly used, its advantages and limitations, and how to determine which option may be best for your property.
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Before choosing a septic system, it helps to understand the main options and how they differ.
Some systems are simple and commonly used for residential properties, while others are designed for sites with drainage challenges, limited space, or stricter treatment needs. The sections below break down each system in plain language so you can understand how it works, where it is typically used, and what to consider before installation.
A conventional septic system is the most common septic system used for residential properties in Ontario. It typically includes a septic tank and a leaching bed that work together to collect, treat, and disperse wastewater through the soil.
These systems are often selected because they are reliable, cost-effective, and well suited for properties with suitable soil conditions and enough space for a septic bed.
Wastewater flows from the home into the septic tank where solids settle and begin breaking down naturally. The partially treated liquid then moves into the distribution system and enters the leaching bed, where surrounding soil provides additional filtration.
For many homeowners, a conventional septic system remains the preferred choice because it balances performance, simplicity, and cost. However, proper soil testing, site evaluation, and system design are still essential before installation.
A chamber septic system is similar to a conventional septic system but uses plastic chambers instead of traditional gravel trenches. These chambers create open space that allows wastewater to move and disperse into the surrounding soil.
Chamber systems are often used when installation flexibility is needed or where reducing gravel use is preferred. They still rely on soil treatment but use a different distribution method.
Wastewater first enters the septic tank where solids settle and begin breaking down. The liquid wastewater then flows into connected plastic chambers installed below ground. These chambers replace gravel trenches and provide space for wastewater distribution and soil contact.
A chamber septic system can provide similar performance to a conventional system while reducing the need for gravel trenches. For some properties, it offers added installation flexibility without changing how the system functions overall.
A mound septic system is used when the natural soil conditions on a property are not suitable for a traditional underground leaching bed. Instead of placing the treatment area fully below ground, a mound system uses a raised engineered bed to treat and disperse wastewater.
These systems are often selected for properties with high groundwater, shallow soil, poor drainage, or bedrock close to the surface. While they are more complex than conventional systems, they can make septic installation possible on challenging sites.
Wastewater flows from the home into the septic tank, where solids settle and begin breaking down. The liquid wastewater then moves to a pump chamber, which pushes wastewater into a raised mound made from engineered sand and soil. The mound acts as the treatment area.
A mound septic system is often a practical solution for properties where conventional septic systems are not suitable. It may cost more and require additional planning, but it can provide reliable wastewater treatment on sites with challenging soil or groundwater conditions.
An aerobic treatment unit, often called an ATU, is a septic system that uses oxygen to help break down wastewater more efficiently. Unlike a conventional septic tank, an ATU introduces air into the treatment process to support aerobic bacteria.
These systems are often used when a property needs a higher level of wastewater treatment or where site conditions make a standard septic system more difficult to use.
Wastewater enters the treatment unit where air is added to the system. This oxygen supports aerobic bacteria, which help break down waste more quickly and produce cleaner effluent before wastewater reaches the final dispersal area.
Aerobic treatment units can be a strong option when a property needs improved wastewater treatment, but they require more maintenance and mechanical support than a conventional septic system.
A sand filter septic system uses a layer of engineered sand to provide additional wastewater treatment before the water moves into the final dispersal area. The sand acts as a filtration layer, helping improve treatment when natural soil conditions alone may not be enough.
These systems are often used when a property needs better filtration or when site conditions require an added treatment step before wastewater reaches the soil.
Wastewater first enters the septic tank, where solids settle and begin breaking down. The liquid wastewater then moves through a sand filter, where engineered sand helps remove contaminants and improve treatment quality before final dispersal.
A sand filter septic system can be a good option when a property needs added wastewater treatment. It provides more filtration than a basic system, but it also requires careful design, proper installation, and regular maintenance.
Advanced treatment systems are designed for properties where a standard septic system may not provide enough treatment or where environmental conditions require a higher level of wastewater processing.
These systems use additional treatment stages, filters, media, or biological processes to improve wastewater quality before it reaches the final dispersal area. They are often used on difficult sites, environmentally sensitive properties, or locations with stricter treatment requirements.
Wastewater enters the septic tank where initial settling takes place. After that, it moves through additional treatment stages such as filters, specialized media, biological treatment processes, pumps, or enhanced filtration systems.
Advanced treatment systems are often used when site conditions, environmental concerns, or property limitations make traditional septic systems difficult. They provide more treatment capability, but usually involve higher costs and more maintenance.
A holding tank is different from a traditional septic system because it stores wastewater instead of treating and dispersing it through a septic bed. Wastewater remains inside the tank until it is pumped and removed by a licensed service provider.
Holding tanks are usually considered when a property cannot support a conventional or advanced septic system, or when a temporary or seasonal wastewater solution is needed.
All wastewater from the home flows into a sealed tank. Unlike other septic systems, there is no leaching bed or final treatment area. Once the tank fills, it must be pumped out and emptied.
A holding tank may solve certain site limitations, but it is not the same as a full septic system. Because it only stores wastewater, homeowners need to plan for regular pumping and ongoing service costs.
Choosing a septic system is not simply about selecting the most common option. The right system depends on the property itself and whether the site can support a traditional installation or requires an engineered solution.
Several factors influence what type of septic system may be suitable.
Soil Conditions: Soil plays a major role in how a septic system performs. Drainage rates, absorption, and soil composition help determine whether a conventional system is possible or if a different design may be required.
Groundwater Levels: Properties with high groundwater often need additional separation between wastewater treatment areas and the water table. This can influence the type of septic system that may be used.
Lot Size & Available Space: Some septic systems need more room for treatment areas, septic beds, or raised mounds. Smaller properties may require alternative or advanced solutions.
Drainage & Site Conditions: Poor drainage, slopes, shallow soil, nearby water bodies, and other site conditions can affect system design and performance.
Household Size & Water Usage: Larger homes and higher water use generally produce more wastewater, which may affect system size and design requirements.
Local Regulations & Permits: Septic systems in Ontario must meet design requirements, setback distances, environmental standards, and approval processes. Regulations may influence which systems are suitable for a property.
Every property is different, and the ideal septic system depends on factors such as soil conditions, groundwater levels, drainage, available space, household size, and local requirements.
While some homes are well suited for a conventional septic system, others may require a mound system, advanced treatment system, or another engineered solution based on site conditions.
Choosing the right system early can help improve long-term performance, reduce future issues, and ensure the installation fits the property properly. Contact us today for a free consultation and estimates.
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