22Aug, 2022
    Focus On: Septic Tank vs. Treatment Plant

    Septic tanks and sewage treatment plants (STP’s) are often confused as the same thing, however they are not.  

    How do they work?

    A STP works in a similar way to a septic tank by acting as a trap for the solid waste and discharging the waste water but with a big difference; STP units are designed to treat the wastewater before it is discharged, and is therefore permitted to discharge to a watercourse such as a river, stream or pond and in many instances can be discharged into a storm water soak-away.

    What are the differences?

    • STP’s require electricity to run the air pump and other mechanical components however septic tanks can run power-free
    • Septic tanks don’t require servicing (although they do require emptying), whereas sewage treatment plants require servicing and emptying.
    • A typical septic tank has two ‘zones’, whereas a sewage treatment plant typically has three.
    • A STP provides treatment of the waste, whereas a septic tank simply separates it – this means that the waste water that leaves a STP is cleaner than what leaves a septic tank. 

    Septic Tank

    Sewage Treatment Plant

    What does this mean to you? 

    There are a lot of properties out there which currently have a septic tank that discharges to a local watercourse (instead of to a soakaway system or drainage field). As of January 1st 2020, this is no longer legal. 

    If you own a property with this drainage system, you must upgrade it by that date. If you are selling a property with this system in place before 2020, you must upgrade it before selling. If you are buying a property with a septic tank discharging to a watercourse and this hasn’t yet been discussed – don’t until agreement has been made about upgrading the system. 


    For more information about the General Binding Rules read our blog here, or speak to our team.

    1Aug, 2022
    Do you meet the General Binding Rules?

    Industry standards released by the Environmental Agency in 2015, mean any sewage treatment plant that discharges wastewater must meet strict regulations. 

    If your treatment system was installed before 1983 you do not need to do anything, as there was no British Standard in place before then. You must, however, still meet the other general binding rules that apply to you.

    The new January 2020 General Binding regulations are thorough and rules depend on how much you discharge, where you discharge and if you are a commercial entity. 

    Some of the key standards outlined in the regulations are: 

    • Discharge can only be domestic sewage
    • In an area where the water level changes depending on the tide, discharge must be below the mean low water spring mark.
    • Plant must meet the relevant British Standard.
    • Plant must be the correct size for the amount of sewage it will need to treat. This should meet the sizing requirements in British Water’s guidelines.
    • Regular maintenance in line with manufacturer’s instructions should be adhered, and it the system must always be in good working order
    • The system must be regularly emptied – once a year or in line with the manufacturer’s instructions. The company used to dispose of the waste must be a registered waste carrier. 

    If you’re not sure if you meet the regulations, reach out to our team who can advise you on the system right for you and of our standard practices for installation and maintenance.