Sewage Treatment in the UK


Certificates and tests

When installing any sewage treatment product at a property it is important to ensure that it conforms to the current European standard and has been tested by and approved by an official agency such PIA in Germany and passed the minimum test requirements - this ensures that the tank is certified to EN12566-3. If in doubt ask to see the results certificate for a tank, these should be readily available from the manufacturer or sales agent. If the certificates are not forthcoming then beware some manufacturer’s claim their product “meets” EN-12566-3 this does not mean that is has been tested and passed.


What comes out the other end.....of the tank!

The effluent quality that is discharged from a sewage treatment plant will be of a much better quality than that from a traditional septic tank and soakaway. At Matrix Sewage we only supply sewage treatment plants, the reason for this is that we believe the grey water discharge from these plants exceeds traditional septic tanks – for example the Matrix plant BOD is 96.2% - the Environment Agency recommends a minimum of 94%



Environment Agency

We recommend that all buyers familarise themselves with the rules around installation of a sewage treatment plant – in particular please note that the Environment Agency is currently updating the registration process for England.


Environment Agency – Current Position on Sewage Treatment Plants

  • Discharge is to surface water and is of 5 cubic metres per day or less;
  • Sewage is only domestic, meaning effluent from residential properties and services that originate predominantly from the human metabolism and from household activities. Domestic sewage includes wastes arising from normal domestic activities wherever these are carried out. Therefore, sewage from for example, residential homes, restaurants, takeaways and nursing homes is domestic.
  • The sewage system is maintained in accordance with the manufacturer’s instructions and you must keep a record of all maintenance. (Where manufacturer’s instructions are not available please refer to the "British Water Codes of Practice and Technical)
  • Discharge does not cause pollution of surface water or groundwater.



At the moment the Environment Agency do not require registration for small sewage discharges in England that meet the above criteria, and they will not take enforcement action against septic tank owners unless a discharge has caused, or is likely to cause, pollution. There is a more detailed explanation on this enforcement position available on the Environment Agency website


However householders can still register their plant if they wish to do so, perhaps if there is the prospect of a house sale.


Please check with the Environment Agency before purchasing a sewage treatment plant as restrictions remain for "Source Protection Zone1" (SPZ1). We therefore advise all clients to fully establish their own position before purchase.


Please note: the Environment Agency is due to review its position on the above by 31 December 2012.


Environment Agency – Welsh Regulations (Note- these differ from England)


If your property is in Wales you will need to register your sewage treatment plant or septic tank, for most people this is a free registration as long as you meet the criteria listed below:



  • your septic tank discharges into a soakaway in the ground and the property or properties has less than 9 people in total living there;
  • if your sewage treatment plant discharges to a watercourse, and the property or proprieties has less than 27 people living there
  • if the sewage system is not near a protected or designated area for the environment or groundwater supply. For example, a Site of Special Scientific Interest (SSSI) or a Source Protection Zone for drinking water – we can check this for you once we have received your application.



If the above criteria are not met they you will have to apply for an “Environmental Permit” – please see links below on how to do this.




Scottish Environment Protection Agency

In Scotland “Proof of registration” is required when new properties are being built or existing properties change hands under the conveyancing system.

Property owners selling existing properties may find that they already have documentation demonstrating that their tank was registered under older environmental legislation. This documentation is acceptable for the conveyancing process so no further action is needed.

If no evidence of a previous registration can be found, please apply to SEPA.

Sewage pollution poses a risk to the environment and to human health. It is very important that tanks and other small private sewage treatment systems are kept in good order by their owners. If pollution is reported to SEPA by the public, we require the owner to take remedial action and to register their installation. The relevant legislation is Water Environment (Controlled Activities) (Scotland) Regulations which came into force on 1 April 2006. The legislation requires SEPA to recover the costs of dealing with registrations.

The cost of registering a septic tank or small sewage treatment works is £104 by post, or £77 for online applications. This is one-off cost with no ongoing fees. For further information view the Scottish Environment Protection Agency (SEPA) website link below, this gives further details on guides to registration and on-line registration of your sewage treatment plant.

Links :