If you’ve been told your septic tank needs replacing, one of your first questions is probably: how much does it cost to replace a septic tank? Unfortunately, there isn’t one simple number.
The cost of replacing a septic tank in BC depends on the tank itself, the condition of the existing system, access to the property, excavation requirements and whether you’re replacing only the tank or dealing with a larger septic system problem.
Before assuming you need an entirely new septic system, it’s worth figuring out exactly what has failed.
Septic Tank Replacement vs. Septic System Replacement
First, an important distinction: your septic tank is only one part of your septic system.
A typical septic system includes a septic tank, piping and a dispersal area that returns treated effluent to the soil. Depending on the type of system, there may also be pumps, treatment components and other equipment.
If the tank itself has deteriorated or failed but the rest of the system is functioning properly, it may be possible to replace the tank without replacing the entire septic system.
If the dispersal area has failed or the existing system is no longer appropriate for the property, you may be looking at septic system replacement rather than septic tank replacement.
This is why the first step shouldn’t simply be asking, “How much is a new tank?” It should be asking, “What actually needs to be replaced?”
So, How Much Does It Cost to Replace a Septic Tank?
The total cost can vary significantly from property to property.
Replacing an existing septic tank involves more than purchasing a new concrete or plastic tank. The project may include locating and exposing the existing system, pumping the tank, excavation, removal or decommissioning of the old tank, installation of the replacement, reconnecting piping, backfilling and restoring the site.
In BC, replacing an existing septic tank is also considered a system repair or replacement that requires filing. The work therefore needs to be approached as part of the regulated onsite sewerage system, not simply as an excavation project.
The best way to establish an accurate cost is to assess the existing system and property first.
What Affects the Cost of Septic Tank Replacement?
1. The Size of the Tank
Larger homes and higher expected wastewater flows can require larger tanks. The appropriate tank isn’t simply chosen based on what happens to be there now. The existing system and current requirements need to be considered when planning the replacement.
A larger tank also means more material, greater weight and potentially more equipment and excavation to install it.
2. Access to the Septic Tank
Site access can make a major difference.
A tank located in an open area with straightforward excavator and truck access is a very different project from one tucked behind a house, below landscaping or in an area with limited machine access.
Fences, retaining walls, mature landscaping, steep slopes and other structures can all affect how the work needs to be completed.
3. How Deep the Existing Tank Is
Depth affects excavation.
A deeply buried tank requires more digging and creates more material that needs to be handled during the replacement. It may also complicate access and increase the amount of site restoration required afterward.
4. The Condition of the Existing Tank
Why is the tank being replaced?
Concrete tanks can deteriorate over time. Tanks can crack, lids can fail, components can deteriorate and roots can find their way into damaged areas.
Sometimes a problem that initially looks serious can be repaired. Other times, inspection reveals that replacement is the better long-term solution.
Knowing the condition of the tank before starting helps determine the appropriate scope of work.
Does the Entire Septic System Need to Be Replaced?
Not necessarily. A failed septic tank doesn’t automatically mean the dispersal field has failed too.
Likewise, recurring septic problems don’t automatically mean the tank itself is the problem.
Backups, slow drainage, sewage surfacing on the property, unusual odours and other symptoms can have several causes. Problems can occur at the inlet or outlet, within the tank, in pumps or treatment components, or within the dispersal area.
A proper assessment helps determine where the failure is occurring before excavation begins. That can be the difference between repairing one component and unnecessarily replacing an entire system.
Can You Just Replace an Old Septic Tank With the Same Size?
Not automatically.
An existing septic system may have been installed decades ago, and the replacement needs to be considered in relation to the property, the home’s wastewater flow and the rest of the existing system.
BC’s Sewerage System Regulation treats installing, repairing and altering a sewerage system as regulated construction. Depending on the system and work involved, an authorized person such as a Registered Onsite Wastewater Practitioner (ROWP) or professional is involved in the process.
For a tank replacement, The existing system, septic system size and current requirements need to be considered when planning the replacement. BC’s Standard Practice Manual specifically identifies replacement of an existing septic tank as work requiring filing and calls for the components of the system to be assessed.
What Happens During a Septic Tank Replacement?
Every property is different, but a septic tank replacement will generally involve assessing the existing system, determining the appropriate replacement, exposing and dealing with the old tank, excavating for the new tank, installing it at the correct elevation, reconnecting the system and restoring the excavation.
The surrounding components matter too.
The inlet and outlet piping, fittings, filters, risers and other accessible components should be considered while the system is open. If something is already deteriorating or poorly configured, this can be an opportunity to improve how the system functions and how easily it can be serviced in the future.
What If the Septic Field Needs Replacement Too?
This changes the project considerably.
If the dispersal area has failed or the existing system is no longer appropriate for the property, you may be looking at septic system replacement rather than septic tank replacement.
That can involve site and soil assessment, septic design, additional excavation, new dispersal components and potentially a different type of treatment system.
This is also why it’s difficult to give a meaningful septic replacement price based only on a phone call.
Two homeowners can both say, “I need my septic replaced,” while actually requiring completely different projects.
Signs Your Septic Tank May Need Attention
An old tank doesn’t necessarily need to be replaced simply because of its age. What matters is its condition and how the overall system is functioning.
It’s worth having your system investigated if you’re noticing:
- Frequent sewage backups
- Cracks or deterioration in the tank
- Damaged or unsafe tank lids
- Sewage odours around the system
- Roots entering the tank or piping
- Problems at the inlet or outlet
- Unexplained wet areas around the system
- Repeated septic problems despite regular servicing
Finding the cause first is important. In some cases, repairing or replacing individual components may solve the problem without requiring a complete system replacement.
Don’t Wait Until the Tank Completely Fails
Septic systems are easy to ignore when they’re working. When they’re not, they can become urgent very quickly.
If you have an older septic tank or you’ve started noticing recurring problems, investigating them early gives you more opportunity to understand what’s happening and plan the work properly.
It also gives you a much clearer answer to the question that brought you here in the first place: how much will it actually cost to replace your septic tank?
The answer depends on what your property and system need.
Septic Tank Replacement in the Fraser Valley
Kerkhoff Excavating + Septic provides septic system installation, replacement and excavation throughout Chilliwack and the Fraser Valley.
As a Certified ROWP contractor, we can assess the existing system, determine the scope of work and help you understand whether you’re dealing with a tank replacement, a repair or a larger septic system replacement.
If you’re concerned about an existing septic system, get in touch and tell us what’s happening. We’ll help you figure out the next step.