Septic tank conversion units and kits can be classified as two types - BEWARE!
- 'ADD-ON' plants which are installed after an existing septic tank to convert it into a sewage treatment plant which can discharge, legally, directly to a ditch. These must have the EN 12566 Certificate in order for compliance with Environment Agency standards.
- 'IN-TANK' conversion kits which are sold to fit into an existing septic tank to 'convert' it to a sewage treatment plant. These do not have the mandatory EN 12566 Certificate required to qualify for an Exemption and need a Permit from the E.A. before installation occurs. In-tank retrofit kits can only be used if the operator first applies for and is granted an environmental permit..
The EN 12566 test runs for 38 weeks at an independent EN Test Centre. It monitors the performance of the plant under a variety of circumstances - normal use, underloading, overloading, etc. This test costs around £30,000 per plant and you cannot test 'in-tank' systems, as they are not consistent, i.e. septic tanks are different sizes, different shapes, etc. and so there is no EN Test for them as it would be pointless. The only way that you could obtain an EN12566 Certificate for one would be to dig up the septic tank and send it, complete with the 'in-tank' conversion to an EN Test Centre to be tested as a complete system. Unfortunately, this would cost you around £30,000.
The 'in-tank' conversion kits that are available are about the same price as add-on plants, but they require a Permit from the E.A. prior to Installation.
There are three add-on plants that do have the EN 12566 Certificate, as they all have been tested using septic tank effluent, as well as raw sewage. They are: