Septic Tank vs SBDS in Ghana: Which Sewage System Is Better for Your Home?

Septic Tank vs SBDS in Ghana: Which Sewage System Is Better for Your Home?

Choosing the right sewage system is one of the most important decisions to make when building a home in Ghana. Yet, it is often treated as an afterthought.

For many homeowners, the usual choice has been a septic tank and soakaway. But what happens when the system fills too quickly, starts overflowing, develops unpleasant odours, or becomes difficult and expensive to maintain?

This is where alternatives such as the Sisal Biomechanical Drainage System (SBDS) deserve consideration.

So, between a septic tank and SBDS, which sewage system is better for a home in Ghana?

The answer depends on your property, soil conditions, wastewater needs and how the system is designed. However, understanding how each system works can help you make a much better decision before construction begins.

In this guide, we compare septic tanks and SBDS in Ghana, explain how both systems work, examine their advantages and limitations, and show when a SBDS system may be a better option for a residential property.

What Is a Septic Tank?

A septic tank is an underground tank designed to receive and hold wastewater from a property.

Wastewater from toilets, bathrooms, kitchens and other parts of the building flows into the tank. Inside the tank, heavier solids settle at the bottom while lighter materials float to the top.

The liquid portion then needs to move into a soakaway or another suitable drainage arrangement.

A septic tank therefore depends on more than the tank itself. The performance of the overall sanitation system also depends on factors such as:

• Tank size
• Number of people using the property
• Wastewater volume
• Soil conditions
• Soakaway design
• Groundwater conditions
• Installation quality
• Maintenance
• How the system is used

This is why simply installing a large septic tank does not automatically guarantee a reliable sewage system.

What Is SBDS?

SBDS stands for Sisal Biomechanical Drainage System.

It is a sanitation and wastewater management system developed by Sisal Engineering & Construction for properties where public sewer infrastructure does not reach.

According to Sisal Engineering, SBDS treats wastewater biologically and returns it safely to the soil instead of simply storing wastewater until the tank needs to be emptied. The system is available in residential classifications from RC1 to RC7, as well as custom configurations for larger commercial properties such as hotels, schools and estates.

This distinction is important.

A conventional septic tank primarily acts as a containment and settling structure. A properly designed biological wastewater-treatment system takes the treatment process further.

For a homeowner considering SBDS, however, the right system should always be determined based on the property’s requirements and a professional assessment rather than choosing a classification simply because it is available.

Septic Tank vs SBDS: What Is the Main Difference?

The biggest difference is what happens to the wastewater after it enters the system.

A septic tank is primarily designed to hold and separate wastewater and solids before the liquid effluent moves into a subsequent disposal or infiltration system.

SBDS, on the other hand, is designed around biological treatment of wastewater before it is safely returned to the soil.

This means the two systems should not be viewed as exactly the same technology with different names.

Feature	Septic Tank & Soakaway	SBDS
Main function	Wastewater containment and settling	Biological wastewater treatment
Requires a tank	Yes	Uses a dedicated underground system
Depends on soakaway performance	Typically yes	Designed around its treatment and drainage approach
Biological treatment	Occurs within the septic process but is limited	Central to the SBDS approach
Emptying requirements	Periodic desludging is normally required	Designed to reduce the type of failures associated with conventional systems
Suitable for homes without public sewer access	Yes	Yes
System selection	Based on property and site conditions	Based on property requirements and SBDS classification
Larger developments	Possible with suitable design	Custom commercial configurations available

The table provides a general comparison. Actual performance depends heavily on design, site conditions, installation and maintenance.

Why Do Septic Tanks and Soakaways Fail in Ghana?

Septic tanks themselves are not automatically bad systems.

The bigger problem is that poor design, unsuitable site conditions, inadequate capacity and poor maintenance can turn a conventional sanitation system into a recurring problem.

Some common problems include:

1. The soakaway cannot absorb wastewater effectively

Soakaways depend heavily on the surrounding soil.

If the soil has poor infiltration characteristics, wastewater may not move into the ground efficiently.

The result can be:

• Slow drainage
• Standing wastewater
• Overflowing systems
• Wet areas around the soakaway
• Unpleasant smells

This is particularly important when designing sanitation systems for properties where ground conditions have not been properly assessed.

2. The system is undersized

A sanitation system designed for a small household may struggle when the number of occupants increases.

For example, a home initially designed for a few occupants may later accommodate:

• More family members
• Tenants
• Domestic workers
• Visitors
• Additional rooms
• A second household

The wastewater load can increase considerably.

3. Poor construction

Even a good sanitation design can fail if it is poorly installed.

Problems can result from:

• Incorrect dimensions
• Poor materials
• Improper connections
• Poor drainage gradients
• Inadequate site preparation
• Lack of supervision

This is why the contractor and engineering team matter just as much as the system selected.

4. Lack of maintenance

Every sanitation system needs appropriate care.

A homeowner should not wait until wastewater is overflowing before investigating the condition of the system.

Regular inspection and appropriate maintenance can help identify problems before they become expensive emergencies.

5. Groundwater and site conditions

Groundwater levels and soil conditions can affect how wastewater systems perform.

A system that works reasonably well on one property may not perform the same way on another property.

This is one reason professional site assessment should come before choosing a sanitation solution.

How Does SBDS Address These Problems?

SBDS takes a different approach to wastewater management.

Rather than treating the system primarily as a place where wastewater is stored until emptying becomes necessary, SBDS uses biological treatment as a core part of the process.

According to Sisal Engineering, the system treats wastewater biologically and safely returns it to the soil. The company developed SBDS specifically to address sanitation challenges where public drainage infrastructure does not reach.

From an engineering perspective, this approach changes the question from:

“How large should the tank be?”

to:

“How should wastewater be treated and managed appropriately for this property?”

That is an important distinction when planning sanitation for a new building.

Is SBDS Better Than a Septic Tank?

There is no responsible one-size-fits-all answer.

A septic tank can be an appropriate sanitation solution when it is correctly designed, installed, used and maintained for the site.

However, SBDS may be a better option for some Ghanaian properties, particularly where the homeowner wants a professionally designed biological wastewater-treatment solution rather than relying on conventional septic and soakaway arrangements.

The decision should consider:

• Number of occupants
• Number of bedrooms
• Expected wastewater volume
• Soil conditions
• Available space
• Groundwater conditions
• Property location
• Long-term maintenance requirements
• Future expansion
• Type of building
• Local drainage infrastructure

This is why Sisal recommends assessing the property before selecting the appropriate residential SBDS classification. Its residential range runs from RC1 to RC7, covering homes from smaller one- to two-bedroom properties through to seven-bedroom homes.

SBDS RC1 to RC7: What Do the Classifications Mean?

One of the questions homeowners often have is:

“Which SBDS system do I need?”

Sisal Engineering’s residential SBDS systems are classified from RC1 through RC7.

The classifications are designed around different residential requirements, with the range covering properties from one- and two-bedroom homes through seven-bedroom homes.

However, homeowners should not select a system purely from the number of bedrooms.

A professional assessment should consider the actual property and expected wastewater demand.

For example, two houses with the same number of bedrooms may have different wastewater requirements because of differences in:

• Occupancy
• Water usage
• Property type
• Building layout
• Intended use
• Future expansion
• Site conditions

For larger properties and commercial developments, Sisal also provides custom SBDS configurations for facilities such as hotels, schools and estates.

Septic Tank vs SBDS: Which One Costs More?

Cost is naturally one of the biggest concerns for anyone building a house in Ghana.

But comparing only the initial installation price can be misleading.

The actual cost of a sanitation system may include:

• Design
• Site assessment
• Excavation
• Materials
• Labour
• Plumbing connections
• Installation
• Drainage
• Maintenance
• Future desludging
• Repairs
• System replacement

A cheaper installation may become expensive over time if it repeatedly requires repairs, desludging or reconstruction.

Likewise, a more sophisticated system should be evaluated based on its total value over its expected service life, not simply its installation cost.

For this reason, Sisal’s approach starts with consultation and site assessment before design and costing. The company states that it provides free initial consultation and site assessment, followed by clear written costing before work begins.

If you are comparing septic tanks and SBDS for a new home, the best approach is to obtain a professional assessment and compare the solutions based on your actual site.

What Should You Consider Before Choosing a Sewage System?

Before deciding between a septic tank and SBDS, consider these seven factors.

1. Your soil type

Soil affects how wastewater can move through the ground.

A proper assessment can help determine whether the proposed system is suitable for the site.

2. The size of your household

The more people using a property, the greater the potential wastewater load.

Your sanitation system should be designed with expected occupancy in mind.

3. Your building size

Bedroom count can provide an indication of residential demand, but it should not be the only consideration.

4. Available land

The amount of available space can influence the practical design and placement of sanitation infrastructure.

5. Groundwater conditions

High groundwater levels can create additional challenges for wastewater management.

6. Future expansion

If you intend to add rooms, floors or additional units later, the sanitation system should be considered as part of the long-term development plan.

7. Who will design and install the system?

This is one of the most overlooked questions.

A technically appropriate sanitation system can still perform poorly if it is badly designed or installed.

Choose professionals who understand engineering, drainage and sanitation rather than simply hiring someone based on the lowest installation price.

When Should You Consider SBDS for Your Home?

SBDS may be worth considering if:

• Your property does not have access to a public sewer.
• You are building a new home.
• Your existing septic system repeatedly fails.
• Your soakaway is overflowing.
• You want a biological wastewater-treatment solution.
• You are developing a larger residential property.
• You are planning an estate or institutional project.
• You want professional engineering input before installing your sanitation system.

SBDS is not necessarily the answer for every property.

The correct question is:

Which sanitation system is technically and practically appropriate for this specific site?

That is where professional assessment becomes valuable.

Can SBDS Be Used for More Than Houses?

Yes.

While residential applications are an important part of the system, Sisal Engineering also states that SBDS can be configured for larger commercial developments.

Examples include:

• Hotels
• Schools
• Estates
• Commercial developments
• Other properties without suitable public sewer access

For larger projects, the system should be designed around the expected wastewater demand and the characteristics of the development rather than applying a residential configuration without assessment.

Why Professional Design Matters

Sanitation is part of the building’s infrastructure.

It should therefore be considered alongside architectural, structural, plumbing and other engineering requirements rather than treated as something to solve after the house has been completed.

Sisal Engineering & Construction combines architectural, structural and MEP design with construction management and sanitation solutions. Its stated process begins with consultation and site assessment, followed by design and costing, installation and then handover and support.

This integrated approach can be particularly useful when building a new property because the sanitation system can be considered during the design stage rather than being squeezed into whatever space remains after construction.

Septic Tank or SBDS: Which Should You Choose?

If you are building a house in Ghana, don’t choose your sewage system simply because it is what neighbouring houses use.

Your property may have different:

• Soil conditions
• Occupancy
• Water consumption
• Space limitations
• Groundwater conditions
• Development plans

A conventional septic tank can work when it is properly designed and maintained.

But if you are dealing with recurring septic or soakaway problems—or you are planning a new development without public sewer access—SBDS is an option worth professionally assessing.

The key is not simply choosing the newest system.

It is choosing a system that is properly designed for your property and expected wastewater requirements.

Frequently Asked Questions About Septic Tanks and SBDS

Need Help Choosing Between a Septic Tank and SBDS?

Your sewage system should be designed around your property—not copied from another building.

If you are building a new home, dealing with a failing septic or soakaway system, or developing a larger property without access to public sewer infrastructure, Sisal Engineering & Construction can assess your site and help you determine the appropriate sanitation solution.

Sisal provides SBDS systems for residential properties from RC1 to RC7, as well as custom solutions for larger developments such as hotels, schools and estates. The company also combines sanitation expertise with architectural, structural and MEP design and construction services.

Get a Professional SBDS Assessment

Instead of guessing which sewage system your property needs, speak with an engineering team that can assess the site and recommend an appropriate solution.

Request a free, no-obligation consultation and site assessment from Sisal Engineering & Construction.

Call: 0594 081 487

Website: Sisal Engineering & Construction