CIRIA technical note 146 reported that several thousand septic tank soakaways fail each year

Part H2 of the 2000 Building Regulations state that "Septic tank effluent can be harmful". Recent reports issued by the DTLR and CIRIA all point out that septic tank soakaways are a major cause of failure. In all cases a treatment plant should be considered ahead of a septic tank.

It is vital to address off-mains drainage issues as early as possible in your project, in fact your evaluation of the site’s drainage characteristics should influence your assessment of the plot’s overall development potential. You should also draw on local expertise and liaise with the relevant authorities before submitting a planning application. Remember too that individual sites can vary greatly, even within a small geographical area.

Planners

These consult with the Environment Agency as well as Environmental Health and Building Control when preparing planning.

Environmental Regulator

The Environment Agency (EA) in England & Wales,
Scottish Environment Protection Agency (SEPA) in Scotland,
Department of Environment (DoE NI) in Northern Ireland,
Environmental Protection Agency (EPA) in the Republic of Ireland;
are responsible for protecting national water resources and issue Consents to Discharge where appropriate.

Building Control

Responsible for ensuring compliance with the drainage requirements of the Building Regulations.

Environmental Health

Usually consulted by Planning and Building Control before approvals are issued.

Mortgage Providers

May need to be satisfied that the property has a sound and sustainable drainage system.

Construction Insurers

Organisations such as NHBC will provide a warranty on dwellings as long as the installation of the drainage system is in accordance with their Standards. Such insurance is often a prerequisite for successful mortgage applications.