Off Mains Options
To a large extent your choice of off-mains system will depend on a number of influencing factors such as building use, application, site location and ground conditions - but also the system must satisfy the relevant authorities that it will:
- Treat or contain the effluent, providing a long-term sustainable solution
- Be correctly specified to cope with expected usage levels
- Pose no threat to water resources
- Prevent nuisance
In general the options below are listed by order of acceptability, though it must be stressed that each site will have its own specific conditions that will determine the final installed solution.
Pumping waste water off-site to a nearby main sewer should always be considered the primary option.
Under new EPP2 environmental regulations a property located within 30m of a mains sewer is deemed to be in sewered area and will be required to connect to that drainage outlet.
Unless the site assessment can totally justify the use of a septic tank, planning authorities are likely to favour the use of a packaged waste water treatment plant.
Treatment plants accelerate natural treatment processes to produce higher quality effluent which meets strict Permit to Discharge standards. This effluent can then discharge direct to subsoil or to a natural watercourse , subject to approval.
However even treated effluent may not be permissible where porous underlying strata contain valuable potable and ground water resources.
Learn more about Sewage Treatment Plant
Basic Septic Tanks only partially treat sewage and discharge effluent of low quality. Many authorities in the UK prohibit their use.
A septic tank system is likely to fail if it is installed in unsuitable land. For a septic tank to work efficiently the site must have:
- Suitable sub-soil
- Favourable topography and land area
- The correct level of water table which must be at least 1 metre below floor of soakaway trench
- A satisfactory percolation value
- Effluent quality from a septic tank does contain high levels of pollutant and caution must be observed
More advanced products, like the Klargester BioDisc, offer a much higher level of effluent quality, but in all instances a Sewage Treatment Plant should be considered as the first option if a mains drain cannot be reached.
Learn more about Septic Tanks.
Installed when neither a septic tank nor sewage treatment plant would be suitable, a cesspool is a sealed container which provides no treatment to waste water and must therefore be emptied at regular intervals.
It is usually only installed in dense clay, in locations where no discharge point is available, or to serve properties such as holiday homes where usage is intermittent and where water resources require protection.
Learn more about Cesspools