Environment Agency


Depending on your geographical location, soil conditions and the amount of effluent which you wish to discharge it is highly likley that you will need to interact with the Environment Agency prior to installing your sewage treatment package.  This will form a significant part of what packaged treatment system you might be able to install or how the effluent needs to be discharged to the local environment, along with any effluent testing or permitting requirements.

For England and Wales  -  Environment Agency (EA).

For Scotland the Scottish Environment Protection Agency (SEPA) and for Northern Ireland the Environment and Heritage Service. Our customers in Wales will also need to interact with National Resource Wales https://naturalresources.wales

The Environment Agency require you to apply for permits to discharge depending on whether you are planning to:
• discharge in a groundwater SPZ1 area
• in or near a designated sensitive area
• discharge upto 15m3 a day into ground
• or discharge 20m3 a day to surface water
• discharge to the ground where your soil conditions do not meet the required percolation test levels
• discharge if you are within 50 metres of a private water supply (spring, well or borehole)
• discharge in a special area of conservation, in a special protection area, in a Ramsar site or within a biological site of special scientific interest.

Percolation tests which are all mandatory under Building Regulations include three stages which must be followed:

1st stage - Ascertain whether or not your drainage field site is in an area designated by the Environment Agency as a Groundwater Source Protection Zone. If it is, then it means that the groundwater is used for drinking water. A permit to dischargein a SPZ1 would have to be applied for. The EA permit to discharge will include additional conditions to the general binding rules. The Environment Agency will only grant the permit if there is:
• No evidence of pollution
• The risk of pollution is acceptable (quality of the effluent water being discharged)

2nd stage - The Trial Site Assessment Hole (TSAH) This is a single, large hole which is a minimum 2 metres deep. It is to determine that the water table or bedrock never reaches to within 1M of the bottom of the drainage field pipe. If this test fails, we can, however, design an above ground drainage field or contact the Environment Agency and Building Control on your behalf.

3rd stage- The Percolation Tests. If the water soaks away either too fast or too slowly, then a drainage field is not permitted. In general, clay soils will fail and it is not worth performing the tests. This is the test that most people associate with drainage field tests, as it has been mandatory for much longer that the TSAH. The Percolation Test tests the porosity of the soil immediately below and surrounding the 300mm of drainage stone in the trench below the pipe.

Percolation Tests CANNOT be performed at more than 1 metre deep to the bottom of the percolation test hole. This is clearly stated in the Building Regulations and the BS6297 2007 as the maximum depth allowed for soakaway pipework is 700mm, with 300mm of washed drainage stone below this in the trench.

Our MPC Install Team are familiar with all the requirements laid down by both the General Binding Rules and the EA and will work with the agencies to develop a compliant sewage treatment solution for you.