Use code SEWAGE5 for 5% off spare parts orders over £250

Buy With Confidence

We are an authorised seller for major manufacturers

Best Price Promise

If you find the same product cheaper, we'll match it

Same Day Dispatch

On all orders placed before 4pm when items are in stock

Clearwater BioAir CW4 Sewage Treatment System (up to 12 person)

Free & Fast Delivery

Get it when you need it

Secure Payment

Multiple payment gateways

  • Product
  • Data Sheet
  • Free Delivery
  • Need Help?

The Clearwater BioAir CW4 for 12 person applies aeration technology to elevate wastewater quality before discharge. Offering flexible installation, the Clearwater BioAir is designed to suit domestic dwellings with a low visual impact and is supplied as standard with an Isolator Switch and has a standard 12 months standard manufacturer’s warranty.

Clearwater BioAir 4 Gravity Drawing

Clearwater BioAir 4 Pumped Drawing

Clearwater BioAir Blower & Duct Vent Drawing

Clearwater BioAir Installation & Operation Guidelines

Clearwater BioAir PIA Certificate 

Clearwater BioAir 4 Neck Extension

Clearwater BioAir CW4 (12 person) Features: 

  • Suitable for shallow dig Installations
  • Suitable for use in traffic areas (structural design advice required)
  • Low level visibility
  • Improved effluent quality – BOD5 97.5%
  • Third party tested to EN 12566-3
  • Easy to install and operate
  • Supplied with isolator switch (High Level Alarm optional on IPS unit)
  • Affordable service plans available
  • Robust and Lightweight
  • 12 months warranty* (terms apply)

BioAir Applications:

  • Single & Multiple Homes
  • Light Industrial Premises
  • Small Offices
  • Farms
  • Barn Conversions



      BioAir CW4

      Population Equivalent Unit 12
      Daily Flow m3/d 1.8
      Daily Load kg BOD5/d 0.72


      Inlet invert mm 500-2000
      Discharge option
      Gravity / IPS
      Outlet invert (Gravity / IPS) mm 600-2100
      Diameter mm 1920
      Length mm 3238
      Installation depth mm 2245-3745
      Inlet pipe work mm Ø110
      Outlet pipe work (Gravity / IPS) mm Ø110 / Ø50
      Material Construction MDPE or GRP GRP
      Unit Weight kg 500*

      * Tank weight based on 500mm Invert

      Max Inlet Invert Using:
      Gravity Units: Max Invert: 1400mm     
      Pumped Units: Max Invert: 1000mm
      For Inverts from 755 - 1200mm  order 1 X riser  
      For Inverts from 1200 - 1400mm order 2 X risers

      Free Delivery is available to the whole of the UK Mainland (including Scotland) and is subject to suitable access for a large goods vehicle. 

      This product is delivered to the kerb and it is the customers responsibility to provide suitable mechanical offloading facilities (eg. Loader or Excavator) to offload this tank safely. Please specify any access restrictions on your order. 

      HIAB Offload is only available on specific request and will incur an additional cost. If we can do anything to make your purchase more accommodating call our friendly team on 01388 537 050 or email prior to placing your order.

      Lead Times vary but will usually be as follows:

      Clearwater BioAir 2 between 3 - 5 Working Days

      Clearwater BioAir 3 between 3 - 5 Working Days

      Clearwater BioAir 4 between 5 - 7 Working Days

      Clearwater BioAir 5 between 5 - 7 Working Days

      Clearwater BioAir 6 between 10 - 12 Working Days

      Clearwater BioAir 7 between 10 - 12 Working Days

      Clearwater BioAir 8 between 10 - 12 Working Days

      Please always call us if you need your tank on or by a specific date. 

      If you are unsure or need help we are here to help! Give our friendly team a call on 01388 537 050 or email

      You may also need