Septic tank backing up into house

Why a septic tank backs up into the house, what to do first, and how to stop it happening again.

Sam WarrenUKDP co-founder
Published4 May 2020
Updated26 Oct 2026
Read time4 min

Key takeaways

If your septic tank is backing up into your house, arrange for it to be emptied before anything else.
Signs include smells or gurgling from ground floor toilets and sinks, toilet levels rising when flushed, and wastewater seeping from manhole lids.
Tell the tank operator about the backing up, as they may spot damage to the tank or the soakaway pipework.
Water gushing back into the emptied tank from the soakaway pipework can show that the soakaway has failed.
Emptying companies don't carry investigation cameras, so a tank that backs up again after emptying needs a fuller investigation.
If the cause turns out to be damage, your buildings insurance policy may cover the cost of putting it right.

If your property has a septic tank, and you’ve never had any trouble with it, it can be quite a shock when things go wrong. After all, if you can’t even see what on earth is causing the problem, how do you start figuring out what to do about it?

There are many ways that your septic tank can give you a sign that all is not well, and that it might need a bit of TLC. One of the symptoms is if your septic tank starts backing up into your house, which can be the cause for understandable alarm! You might have noticed one or more of the following:

Unpleasant smells or gurgling noises coming from ground floor toilets, sinks, showers or appliances which might be connected to the septic tank
The level in ground floor toilets rising to the top of the basin when flushed (or possibly even overflowing), then very slowly reducing back down to a normal level
Wastewater seeping out around the lid of any manholes near to the property

Suffice to say, if you are experiencing any of the above, you will likely be worried about what might be causing it and what you can do to sort it out.

A septic tank backing up towards the house shows itself through gurgling drains, slow toilets and water rising around a manhole. None of it means the worst, but it does mean the system needs looking at before it gets messier.

What can you do to sort it out?

First things first: in the instance of any problems with your septic tank, the best thing to do before anything else is to arrange for it to be emptied. When the tank is being emptied, explain to the tank operator that the septic tank has been backing up to your house. They might be able to spot problems when the tank is being emptied, such as damage to the septic tank or any soakaway pipework, or perhaps a failure of the soakaway which is causing the septic tank to back up. They may be able to tell if the soakaway has failed because water may gush back into the septic tank from the soakaway pipework once the septic tank has been emptied.

Remember though that septic tank emptying companies don’t carry investigation cameras to be able to carry out a thorough inspection of what’s happening and causing the septic tank to back up into the house. If the septic tank backs up again even after it has been emptied, a more thorough investigation of the problem might be required. At UKDP we have a team of engineers located across the UK, fully equipped to get to the bottom of any septic tank problem you might be having, contact us here to find out more about how we can help.

Whatever the problem you are experiencing with your septic tank, the UKDP team will be on your side, and will work tirelessly to get everything functioning as it should be as soon as possible. Contact us today to find out more.

If it backs up again after emptying, a drainage survey will pinpoint the cause.

Frequently Asked Questions

Why is my septic tank backing up into the house?

Usually the tank is full or the soakaway has failed, so wastewater has nowhere to go but back up the pipes. A blockage between the house and tank can do it too. The first step is to get the tank emptied and see if it returns.

What should I do right now if sewage is backing up?

Stop using water in the house, keep away from the waste for health reasons, and arrange an emptying as soon as you can. We can usually sort this quickly through our tanker partners. If it comes back after emptying, book an inspection.

Does a backed-up septic tank mean it needs replacing?

Not always. If emptying clears it and it stays clear, it was just full. If it backs up again soon after, the soakaway has likely failed, and that's when replacement comes into it. A survey tells you which.

Is a septic tank backing up covered by insurance?

It can be, where a sudden, accidental fault caused it rather than age or missed emptying. We can inspect it, find the cause and help with the claim if there's one.

Why does my septic tank back up when it rains?

Heavy rain raises the groundwater and saturates the soakaway, so a system already near its limit backs up. It can also mean rainwater is wrongly plumbed into the tank. A dye test during an inspection checks for that.

About the author

Sam Warren

UKDP co-founder

Sam Warren co-founded UKDP with James Warren in 2009 as an off-mains drainage specialist.

Did you know?

If there’s damage, it’s possible that the costs to put it right might be covered by your existing buildings insurance policy. We can help from start to finish, as experts both in septic tanks and insurance claims (yes, we realise it’s a little niche, but, as perhaps you are discovering, we do serve a need), from investigating the problem, to checking whether you have the right cover, preparing a report for your insurer and liaising with them through to completing any works agreed to get you back to normal as soon as possible. Find out more about how we work here.

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