EXPERT ADVICE
How to know when your septic tank needs emptying
Updated 03/26
By: Emma Potter
Reviewed: Alex Peters
No one wants to be faced with a overflowing septic tank. Learn the telltale signs that your septic tank needs emptying and how much you can expect to pay in this essential guide.
Sights and smells to look out for
Places to check for extra water or damp
What can happen if it overflows
How to book an emptying service
An overflowing septic tank can be unpleasant and costly to deal with. It could also land you in murky waters with your local authorities or the Environment Agency.
Fortunately, the signs that your septic tank needs emptying are simple to spot.
Keep reading to learn the telltale signs that your septic tank needs emptying. We also explain what happens if your tank overflows and how much a waste disposal expert will charge to fix it.
How do you know when your septic tank needs pumping?
Booking routine tank empties with a qualified waste removal expert will keep your septic system running efficiently and safely. If you have the correct tank size, you’ll only need to empty it on average once or twice a year.
However, it’s always a good idea to look for any warning signs that it needs to be emptied sooner. They are:
1. A foul smell
An unpleasant smell from your sink, shower or bath drains could indicate that your septic tank needs to be emptied. The odour is often more obvious at night when there isn’t as much water running.
If you’ve experienced a period of heavy rain or had more guests in your home than usual, the tank may fill quicker than usual.
Either way, you’ll want to investigate, as sometimes a foul odour could mean the septic tank or soakaway (which safely removes wastewater) has become blocked.
2. Sluggish drains and gurgling sounds
Is water draining more slowly from your sinks, baths, or showers? Or have you noticed a gurgling sound as the water drains away? This could indicate that your septic tank is full or the drainage pipes are blocked.
If ignored, it could lead to overflowing. So, it’s best to nip it in the bud immediately with the help of a waste disposal expert.
3. Waste backup
If you notice discoloured water backing up in your showers and sinks, you’ll want it seen to fast by a qualified waste disposal professional or a specialist plumber.
Use minimal water until the issue is solved, and avoid running baths or using the dishwasher. Otherwise, you could make things worse.
4. Low water flow
If you notice a significant drop in water pressure, it might be another sign that your septic tank needs emptying.
Low water flow sometimes means the waste in your septic tank is not moving through the drainage system efficiently and needs looking at by a specialist plumber.
5. Wet, squishy grass
Have you noticed wet, squishy grass, unusually green grass patches, or water puddles near the septic tank? Unfortunately, this could mean your septic tank has overflowed.
A specialist must deal with this immediately, as the ground surrounding the tank and soakaway may have been contaminated by untreated sewage, which can get into your water source. There's more information about that next.
As a guide, most septic tanks should be emptied every three to five years, depending on tank size, number of people and appliances in the household.
What happens if my septic tank overflows?
Has your septic tank overflowed and contaminated the soakaway or other ground? You'll need a specialist to remove the contaminated soil, which costs around £40/m³.
Sometimes, you may need to wait a few days for the area to dry out before a tradesperson can access it. They will also advise you to avoid using water until the issue has been solved.
While this is not ideal, it could prevent the problem from worsening or you being fined by local authorities. Under current UK legislation, allowing a septic tank to overflow or leak is an offence.
In extreme cases, if your septic tank overflows and pollutes a nearby river or other watercourse, the Environment Agency may also take legal action against you. So, it is vital to take immediate action with the help of a specialist.
How do you find a septic tank specialist?
Trying to fix a septic tank problem yourself is never a good idea. It could invalidate the warranty on your tank or home insurance cover.
That’s why we always recommend hiring a waste disposal expert to empty your tank or carry out any repairs.
Use our search tool below to find a local tradesperson and get a personalised quote.
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How much does it cost to empty a septic tank?
The average cost of emptying a septic tank is between £120–£350, depending on the tank size.
If you'd like an expert to clean the tank with a chemical treatment at the same time, this will be an additional cost of £200.
Read our septic tank emptying cost guide to get more costs.
Find septic tank pumping services near me
Pumping is the method used to empty your septic tank. You should generally pump your septic tank at least every three to five years. But sometimes, you may need to do so sooner. Here, we’ll share all you need to know about septic tank pumping services near you – from when you might need them, to who
Other frequently asked questions
How often should septic tanks be pumped?
The right-sized tank for your home should only need emptying once or twice a year at most. For larger tanks, this may be even less.
How do you know when your septic tank needs emptying?
Tools exist to help you measure how full your tank is. Whether that is via electronic devices (such as float switch alarms) or physical measurement tools (such as sludge sticks).
Can I empty a septic tank myself?
Under the 2020 regulations, emptying a septic tank is a criminal offence unless you are a qualified waste disposal professional. Therefore, you must always use a qualified professional.
Does a new septic tank require planning permission?
Unless it’s a like-for-like replacement, your new septic tank will need building control permission and consent from the Environment Agency.
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