Mantair Septic Tank Conversion

MantairThe term "septic tank conversion unit" refers to a sewage treatment system which fits within an existing septic tank or cesspool. The first septic tank conversion unit was designed over two decades ago by Andrew Skilling of Mantair Limited to provide homeowners with septic tank problems the opportunity of upgrading their septic tank into a fully functioning sewage treatment plant.

As the original pioneers of the conversion unit concept Mantair is still today the market leaders in the field of septic tank and cesspool upgrades. With over 5000 units installed throughout the United Kingdom, Ireland, mainland Europe and West Africa, the Mantair system is regarded by many Regulators and Specifiers as the reliable 'in tank' conversion unit. The Mantair unit has been installed on vary applications including National Trust Nature Reserves, SSSi and RAMSAR Sites. 

Complies with Environment Agency Permit requirements

Designed to fit completely within an existing septic tank or cesspool, the Mantair conversion unit will 'convert' an existing tank producing a clear, odourless and harmless effluent suitable for discharge direct to a ditch, river or stream. The Mantair conversion unit is ideal for situations where the existing septic tank is discharging untreated effluent to a watercourse or where the soakaway has failed and is causing flooding in the tank. The Mantair unit is also ideal for 'converting' cesspool holding tanks, removing the need for frequent emptying.

The Mantair septic tank conversion unit can convert the majority of septic tanks and cesspools, whether manufactured from GRP of constructed from traditional materials. Each Mantair unit is purpose built to suit the existing tank.

All units are designed to ensure that the completed installation will comply with the requirements of the Environment Agency in England and Wales or Mantair septic tank conversion unitSEPA (Scottish Environmental Protection Agency) for the discharge of effluent direct to a natural watercourse.


  • The Most popular septic tank upgrade system in the UK for over 22 years;
  • Does not require the installation of any additional tanks and avoids the disturbance if established gardens;
  • No electrical, mechanical or moving parts within the underground treatment zone;
  • Provides an affordable, discreet and reliable solutions to septic tank problems;
  • Removes the need for frequent emptying or septic tanks or cesspools;
  • Designed to produce a treated effluent in compliance with the Regulating Authorities;
  • Peace of mind with a Lifetime Process Guarantee and Patent Protected.

How it works

The Mantair septic tank conversion unit is powered by a small air blower, which can be located in either an existing outbuilding or in a beehive - a purpose built housing designed to blend into the natural setting. The air blower is the only electrical component of the Mantair system.

The blower can be located up to 25 metres from the Mantair unit and is powered by domestic 240v electrical supply. It is connected to the Mantair unit by a small bore MDPE pipe concealed underground. The blower provides the air that is required for the treatment process and to lift the treated effluent to the discharge point.


Once the Mantair septic tank conversion unit is installed, sewage entering the tank discharges into the Aeration / Mixing Zone. Air is supplied to this zone via an aerator contained within a draught tube. Large and heavy solids are deposited in the Primary Settlement Zone.

The aeration and mixing encourages the growth of aerobic micro-organisms which degrade the sewage.

The contents of this zone, where the micro-organisms are mainted in suspension, is referred to as the 'mixed liquor'. As further flows enter the tank, mixed liquor is displaced into the Final Settlement Zone. Here the micro-organisms separate to form a thin sludge, which is continuously retruned to the aeration / mixing zone, thus maintaining the levels of micro-organisms in the mixed liquor.

The liquid which remains in the final settlement zone is the treated effluent which is discharged from the system via the Final Effluent Airlift. The final effluent airlift controls the rate of discharge from the system and prevents any shock hydraulic loads from affecting the treatment process. The use of the airlift enables the Mantair conversion unit to discharge the effluent at a higher level than the drainage inlet into the tank.


Mantair septic tank conversion units are supplied and installed by the Mantair Contracts Division and network of approved Mantair Licensed Contractors. They are not available through wholesale or retail outlets.

To verify if your installer is a Certified Mantair Licensed Contractor, call Mantair Limited on 01255 476467.

Installation Procedure


Mantair SurveyStage 1

The first stage is to have a Mantair trained engineer carry out an initial survey of your existing septic tank or cesspool. This enables the condition of the existing tank to be assessed and to ascertain the dimensions required by Mantair to manufacture your septic tank conversion system. Each Mantair conversion unit is custom built to suit the existing septic tank or cesspool.


Septic Tank Conversion UnitStage 2

The second stage is the on - site installation. The Mantair unit when installed stands on the floor of the existing septic tank or cesspool. The tank must therefore be emptied and all debris removed from the floor of the tank prior to the installation taking place.



Mantair Ancillary WorksStage 3

As the Mantair unit fits completely within the existing tank and does not require the installation of any new tanks, on the majority of sites only minor civil engineering works need to be carried out. This minimises the disturbance to established gardens.



Completed Mantair InstallationStage 4

Finally the unit is commissioned by a Mantair trained engineer to ensure optimum operational effectiveness of the Mantair conversion unit.




Maintenance is essential to all sewage treatment systems. Maintenance of the Mantair septic tank conversion unit is simple, and comprises the renewal of the air blower inlet filter and flushing through of pipe work and components. Regular maintenance is essential to ensure the efficient operation of the Mantair unit.

The Mantair Maintenance Division together with the Mantair network of Licensed Contractors offer a full after sales service, including planned maintenance visits.

Mantair recommends that all Mantair septic tank conversion units are serviced and maintained by either the Mantair Maintenance Division of a trained Mantair Licensed Contractor. No other organisations are trained in the maintenance procedure of Mantair units.

Guaranteeing Peace of Mind

Unlike any other septic tank conversion unit, the Mantair system comes with a Process Guarantee for the lifetime of the installation. On commissioning of the completed installation, Mantair Limited provides the end user with a Process Guarantee for the final treated effluent produced from the system.

If you have a septic tank problem and would like further information on the Mantair septic tank conversion unit visit or call 0800 121 6786.  


0800 121 6786
01255 476 467



 © Mantair Limited 2011