What does a septic tank replacement cost?
What drives the cost of replacing a septic tank, and when buildings insurance covers it.
Key takeaways
- It depends on why it needs replacing, and if the tank is damaged your buildings insurance may cover it, leaving you to pay only your policy excess.
- Most buildings insurance policies cover damaged drainage systems, so you don't need separate septic tank insurance.
- Covered damage includes splits in the tank walls, tree root damage and broken baffles or dip pipes.
- Insurance won't cover replacing an undamaged tank, for example when you extend the property.
- Without insurance, the cost depends on the tank's size and make, the ground conditions and whether you need a new drainage field or outlet.
- The total cost will be more than the price of the tank itself.
- If you think your tank is damaged, check whether your buildings insurance covers it before paying for a replacement.
You’ve noticed some unpleasant smells in your back garden. You might have even been told by your septic tank emptying company that your tank is damaged and needs to be replaced. Unfortunately, septic tank problems can be trouble both for your nose and your bank balance. So you’re probably wondering, what does a septic tank replacement cost?
Let’s be honest, no one dreams of spending their hard earned savings on a shiny new septic tank. But by the same token, no one wants to live without a properly functioning drainage system. Septic tank problems can range from nasty niffs through to waste water pooling in your garden, so it’s best to get things dealt with as soon as possible.

Replacing a septic tank is a full excavation and install job, not a patch repair, so the price depends on the tank, the ground conditions and site access. How much you pay also comes down to why the tank needs replacing, which is where buildings insurance can come in.
What will my septic tank replacement cost?
There’s no straightforward answer to the question of ‘how much does a septic tank replacement cost’. I know, I know, that’s the only reason that you’re reading this, is to find out the answer! But before you disappear in search of a better answer, I might have some good news for you. You see, it all depends on why your septic tank needs replacement. There’s a chance that our team might be able to get you a replacement septic tank for the cost of your buildings insurance excess. Hopefully, that sounds a lot more palatable!
Here at UKDP, we specialise in helping with insurance claims for damaged septic tanks, cesspits, sewage treatment plants and soakaway systems. Pretty niche, right? But if your septic tank is damaged, you have come to the right place! Most people don’t realise that the majority of buildings insurance policies provide cover for damaged drainage systems, you don’t need to have any specific septic tank insurance in place. The trick is in knowing what is and isn’t covered, and how best to present the information to insurers. Let’s not forget needing to make sure that any works undertaken are compliant with any legislation. Luckily for you, we do this every day, and we like to think we’re really quite good at it.
What type of damage is covered by buildings insurance?
So what type of damage is covered? It’s things like splits in the walls of the tank, tree root damage, broken baffles and dip pipes (sorry, got a bit technical there). If your tank has suffered some sort of physical damage, give us a call and we can let you know whether it’s likely to be covered by your buildings insurance.
If it is, we can pop out to take a look, and help you with the claim. Where a claim is accepted, you normally pay only your policy excess. Sounds good? Get in touch, we’d love to chat septic tanks with you.
If your tank isn’t damaged, and you’re looking to replace it for another reason such as extending a property, that wouldn’t be covered. How much it will cost will depend on various different things, such as:
- the size and make of the tank
- the ground conditions at the property
- whether the septic tank replacement needs a drainage field or other outlet installing
The actual cost of a septic tank replacement will, of course, be more than the cost of the tank itself, but how much more depends on the above factors. If your tank is damaged, call us today and we’ll get things sorted for you as soon as possible.
Frequently Asked Questions
How much does a new septic tank cost to install?
A new septic tank installation typically costs between £10,000 and £12,000. The figure depends on the tank size, your ground conditions, access to the site and whether a new drainage field is needed. We give a fixed quote after a survey rather than a guess over the phone.
Is replacing a septic tank the same cost as a brand-new installation?
Broadly, yes. The work is much the same, so a replacement sits in the same £10,000 to £12,000 range. Decommissioning the old tank is included in the quote, so that isn't an extra.
What happens to the old tank when you replace it?
We usually install the new tank alongside the old one, then empty, clean and collapse the old tank in and backfill it with compacted material so the ground stays stable. It's left safely in the ground, and that work is part of the quoted price.
How often does a septic tank need replacing?
There's no set lifespan and no schedule for it. You replace a tank when it has failed or no longer meets the regulations, not at a fixed age. Many systems run for decades with regular emptying and a working drainage field.
Does a replacement include a new drainage field?
Sometimes. If the drainage field has failed alongside the tank, it's replaced too and sized with a percolation test from £950. That's one of the main reasons replacement costs vary, so a survey establishes exactly what your system needs.
About the author
Sam Warren
UKDP co-founder
Sam Warren co-founded UKDP with James Warren in 2009 as an off-mains drainage specialist.
Need help with your septic tank or drainage?
Reach out to us on 0800 028 9903. Our team are here to talk Monday to Friday 9am to 5pm.
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