Non mains drainage systems

Sometimes properties are too far away from a main sewer for connection to it to be possible. In these circumstances there are several alternative systems available:

Septic tank

    A septic tank is a two or three chamber system, which retains sewage from a property for sufficient time to allow the solids to form into sludge at the base of the tank, where it is partially broken down. The remaining liquid in the tank then drains from the tank by means of an outlet pipe. The effluent normally flows into a soakaway to percolate into the ground, provided that the disposal does not generate a pollution risk to surface or ground water resources.

    Septic tanks normally require de-sludging every twelve months. Avoid using bleach, disinfectants or germicides as these will kill the bacteria which digest the waste.

    Package sewage treatment plants

    Package sewage treatment plants are self-contained units for the treatment of sewage, or units which treat effluent from septic tanks to a higher standard. They must be properly installed in order to operate effectively. The effluent from a package plant is normally suitable for discharge directly to a watercourse.

    Reed beds

    Reed beds are specially designed and constructed plots with a gravel medium and an impermeable base which can be used to improve effluent quality.

    Waterless chemical toilets

    Waterless chemical toilets are self-contained systems which rely on biocides, in one form or another, to control the production of foul odours. They are used on campsites, construction sites and at large events.

    Composting toilets

    Composting toilets use natural processes to convert waste matter into compost and do not involve a liquid discharge. They are useful for remote sites, such as nature reserves.


    A cesspool is a covered watertight tank used for receiving and storing sewage and has no outlet. A cesspool requires regular emptying and must not be allowed to overflow