Septic Tank Installation
Septic tanks are a popular waste water and sewage treatment process for properties where there is no mains sewer connection. By effectively separating solid and liquid waste (and keeping out the rain) they can manage your sewage waste and wastewater by allowing liquids to safely seep into the surrounding earth via a soak-away/drainage field. The following is intended to be a brief installation overview – if you are thinking about installing a septic tank, we would recommend you contact us for more advice.
Positioning
Generally, the minimum distance a tank is positioned from habitable buildings is 15metres, but this may vary according to local authority regulations, and early approval based on these is required. For more information please see our sewage regulations page at UK Septic Tanks.
For obvious reasons consider the direction of the prevailing wind, and do not site the tank close to a drive, roadway or where there is a risk of additional loads being superimposed. Ensure there is good access for the sludge to be removed by an emptying tanker.
Size
This will depend on how many people could live in the property to be connected – for more details about calculating this please see our UK Septic Tanks website.
Installation
The tank will need to be lowered carefully onto a level wet concrete base, gradually filled with water in such a way to ensure an equalising of internal/external pressure and avoids tank flotation during installation. Back filling is then completed up to ground level.
Note: this information assumes “dry” ground conditions – this means at no time does ground water rise above the base of the tank. If you do not have these conditions, please contact us for further information.
Ventilation
It is a requirement that ventilation of the tank (BS6297) occurs without releasing any gases into the air at the tank lid(s), allowing them instead to pass back up the soil vent stack. A separate vent should be provided at the head of the soak away.
Manhole Cover
This needs to be a pedestrian duty cover, manufactured in tough, durable rotationally moulded polyethylene that fits directly onto the neck of the tank.
Effluent Disposal
Septic tank waste water and effluent cannot be permitted to flow directly into a watercourse but must be discharged into the underground strata. Please click this link regarding septic tank regulations for more information.
If discharge is into porous subsoil material such as gravel, sand or chalk, and occurs above the winter water table level then a soakaway pit may be used. For more information about constructing a septic tank soakaway, please visit our UK Septic Tanks website.