empty/ desludge FAQ's

How often should I empty my septic tank?

Your Septic Tank needs to be emptied at least once a year to maintain its efficiency and to prevent damage to the Soakaway.  Some people believe septic tanks don’t have to be emptied at all, however if too much sludge builds up within the septic tank it will wash through into your soak away and cause blockages (not to mention polluting the surrounding land and water courses). Every septic tank is designed to handle a certain volume of waste, if the number of people using the tank increases; you might need to have the tank emptied more than once a year or look to increase the size of your tank or soakaway.

How often should I empty my cesspool?

A Cesspool is simply a holding tank - it doesn't treat the contents. So regular emptying is crucial to stop waste flowing back into your home or business. A cesspool must be emptied when it is almost full, we recommend fitting an alarm system to let you know when it's ready to be emptied.

What is sludge?

Sludge is a combination of inactive solids (which come from bathrooms, kitchens and laundry rooms) and dead biological matter (micro-organisms that aid the breakdown process). All of this settles at the bottom of the tank, which is why it needs removing at least annually.

How do I know if my cesspool, septic tank, sewage treatment plant or pump station needs emptying/ desludging?

You'll notice one or a combination of these problems:

  • Sewage rising up from your tank or soak-away

  • Bad smells coming from your tank

  • Seeing raw sewage in a local watercourse

  • Toilets, sinks and showers backing up or taking a long time to drain

  • Overflowing toilets or sinks

  • Full inspection chambers (these should usually be empty)

  • Boggy grass around your soak-away.

How much does it cost to empty/ desludge?

The cost of emptying/ desludging varies depending on the type of tank you have, where you are and the volume you have removed.


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What do I need to know about tank desludging?

First of all, you need to get the professionals in. By that we mean registered waste carriers. So make sure you check that whoever you use is fully registered. Otherwise you face a first-offence fine of up to £20,000 from the environment agency.

This applies to the 'waste producer' (you), the tanker company removing the waste and the water company who will dispose of it. You also need to keep copies of all documentation from the tanker operator for a minimum of two years.

How do I know I’m dealing with professionals?

Three things:

  • Ask for their waste carrier number and check it with the EA

  • Ask where the waste is being transported to. Sewage should always be taken to a licensed waste reception facility or a sewage treatment works.

  • Make sure you are given a waste transfer note. This should describe the quantity and type of waste that's being removed and where it's going for disposal, along with the date and company details.

If in doubt, check with the Environment Agency.

Where does grease come from and how does it collect?

Any business that deals with or processes food is likely to discharge FOGs (fats, oils and greases). FOGs also accumulate when food is cooked and when plates, pans, utensils and crockery are washed. This then solidifies in your pipes and can cause bad smells and blockages, and attract pests too.

How often should a grease trap be emptied?

monthly tanker visits are essential and a legal requirement to prevent fats, oils & grease from entering the public drainage network. most system also have filters that require periodic replacement. 

the uk building regulations (part h 2.21) states that:-

  • drainage serving kitchens in commercial hot food premises should be fitted with a grease separator complying with en 1825-1 and designed in accordance with en 1825-2 or other effective means of grease removal.

bsen 1825 1 and 2 standard states that:-

  • grease traps should be emptied at least once a month or preferably twice a month; 
  • when it is 25% full of grease it should be emptied.

Why should I empty my tank?

  • You'll save money - If your septic tank, cesspool or pumping station isn't looked after, it'll eventually let you down which can be disruptive and expensive. Bear in mind too that once the problems start, it's probably too late. So aim for prevention rather than cure.
  • You'll stay on the right side of the law - Those not connected to the mains sewer are legally bound to look after their sewage systems properly. Anyone not sticking to the rules will be sniffed out and may be prosecuted
  • It can help you sell your property - An unusable septic tank or one in a bad state will lower your property value and could be a major liability.
  • It protects your health - By regularly maintaining your tank, you're helping to prevent the spread of dangerous bacteria and viruses.
  • It protects the environment - If your tank isn't maintained properly, sewage can leak into local watercourses killing plant and animal species for miles downstream.