Delta Sewage Treatment Systems

Clearwater offer a range of effective solutions for domestic and commercial applications and employ the well proven aerobic biological process for the treatment of sewage. For more information about our commercials solutions, please contact our customer service team.

Certificated to European Standard EN-12566

In 2005, a new European Performance Standard was introduced. EN-12566 requires manufacturers to submit their product to a testing regime that accurately measures the performance of treatment plants up to 50 population.

These tests identify how much pollution the treatment plant removes from the sewage, what level of maintenance is required, and what power is absorbed.

By holding EN-12566 certification, the Clearwater treatment plant is approved for an exemption from a permit to discharge under the new EPP2 environmental legislation.

For more information on EPP2 and off-mains regulations please contact us.



Delta 1-2

The best designs are the simplest. So if you require trouble free sewage treatment, you’re sure to be impressed with the Delta. Fluidised, fixed-film biozones are used as the operating process, resulting in a cleaner, quieter and more efficient treatment plant


  • Unobtrusive below ground installation.
  • Suitability for varying invert levels.
  • Excellent durability.
  • Low profile results in shallow depth excavation.
  • Simple maintenance with easy desludging.
  • Compliant with BS EN-12566 Part 3.
  • Proven standards of discharge – 20mg/l BOD, 30mg/l S.S and 10mg/l ammonia in domestic applications
  • Fully CE-marked


  1. Inlet
  2. Primary settlement tank
  3. Biozone treatment tank
  4. Easy access for desludging
  5. Final settlement tank
  6. Cover

Technical Details

Inlet invert (mm) Outlet (mm) Overall Length
(inc. feet) (mm)
Diameter (mm)
Inlet & Outlet Diameter (mm)
Delta 1 450 550 2720 1727 1530 110
750 850 2720 2027 1530 110
1000 1100 2720 2277 1530 110
Delta 2 750 850 3244 2470 1916 110
1000 1100 3244 2720 1916 110
Delta 3 750 850 3976 2470 1916 110
1000 1100 3976 2720 1916 110
Delta 4 750 850 5550 2470 1916 160
1000 1100 5550 2720 1916 160

For further assistance and advice on selecting the appropriate Delta system please contact our Technical Sales who will be pleased to help. We can arrange for one of our local Area Managers to visit your site to advise on model selection and legislation. We can also recommend specialist installers if requested. This advice service is supplied free of charge. Clearwater also offers reliable solutions for commercial applications. For more information, please contact us.