HiPAF® compact (HPC)

Discover the HiPAF® compact (HPC)

1 up to 60 population equivalent (PE) where mains drainage is unavailable

The below ground HiPAF compact (HPC) wastewater system uses no chemicals and treats to a high standard for more stringent standards stipulated by the Environmental Agency.

The HiPAF is preferred choice for sensitive locations such as Sites of Special Scientific Interest (SSSI) and is ideal for locations which need extra consideration such as a burn, nature reserve, fisheries, salmon river or close proximity to water extraction (well).

Specified by the highly regulated water utilities.



Typical commercial uses

Commercial buildings and offices

Stately homes and country estates

Small hotels and B&Bs

Small retail such as farm shops


Typical domestic uses

Domestic housing

Small villages, rural communities and housing associations

Why choose the HiPAF compact (HPC):

25 years warranty*

Warranty 25 years on the tank and standard air blower (housed in the kiosk) 2 years

Ease of installation

  • Overall compact design minimises excavation – small footprint size units

Energy savings

  • Energy saving timer – pulse air from the blower(s) into the process – whilst the patented process (biozone) treats wastewater with greater efficiency

Low maintenance

  • No internal mechanical or electrical moving parts within the tank
  • Tankering made easier because primary sludge and humus are stored together

Robust process

  • No odours – most other treatment plants have a separate primary tank which store settled solids and can emit odours; however our compact design has no separate primary tank and is therefore odour-free*



  • UK Building Regulations and Environment Agency guidelines
  • British Water’s Code of Practice – Flows & Loads
  • CE marked to BS EN 12566-3
  • Meets all current legislation under the Environmental Permitting Programme

* Warranty subject to correct installation, consistent influent conditions and regular plant maintenance as per the manufacturers’ instruction.

The compact unit is a three-stage wastewater treatment process

1.  Primary settlement tank

2.  Settled solids at the bottom

3. Biological treatment unit (biozone)

4. Air diffusers at the bottom of each chamber

5. Filter media

6. Settled sludge air lift back to primary

7. Final (humus) settlement tank

  • Primary – Primary settlement is in accordance with EN12255-4, giving the required hydraulic retention time and ensuring that 30% of the BOD will settle out in the primary tank. The HiPAF plants below 500 persons will have sludge storage integral to the primary tank. The primary settlement tank is equipped with baffles to prevent floating scum entering the biological phase of the treatment process. It also incorporates WPL’s unique forward feed system which lowers the level in the tank, during periods of low flow, to provide a buffering capacity for possible surges in the influent.


  • Biological – After primary settlement, the settled liquor flows to the biological treatment unit by displacement and via the air lift forward feed. The biozone is fully segmented internally to eliminate the risk of process short cuts. Each biozone segment is filled with high voidage plastic filter media, where both carbonaceous and nitrifying processes take place, mitigating process risks associated with variable loads. Air to oxygenate the influent and to scour excess biomass from the filter media is introduced continuously below each chamber by a series of diffusers.


  • Final – Following biological treatment the effluent flows into the final (humus) settlement tank where the excess biomass settles out. The humus tank is equipped with air lifts which are arranged to automatically transfer settled humus sludge to the primary tank for co-settlement. The treated effluent flows under gravity to the works outfall.

Looking for technical information?

Technical zone


BS EN 12566-3

Compact HPC plant designed and manufactured to BS EN 12566-3.

Fully compliant

The HiPAF® is fully compliant to UK Building Regulations and Environment Agency guidelines. 


General binding rules

Meets current legislation for exemption from a permit to discharge by the Environment Agency (EA), England, as per the General Binding Rules document.

British Water Flows and Loads code of practice

Designed using the British Water Flows and Loads code of practice, to ensure correct sized tanks.

UK & European patented

The HiPAF® is UK and European patented. 

Accredited ISO 9001

ISO 9001 – Recognised for our Quality Management System requirements for all areas of the business.

Accredited ISO 45001:2018

ISO 45001:2018 – Our mission is to ensure that we enforce standards with our Occupational Health & Safety Management System.

Accredited ISO 14001

ISO 14001 – Recognised for our Environmental Management System compliance.

British Water Packaged Treatment Plant (PTP) Focus Group

Technical Director Andrew Baird has 30 years’ experience in the water and wastewater treatment industry. As a former convenor of British Water’s Package Treatment Plant Focus Group, he has been influential in the development of British and European Standards and continues to promote good practice in design, installation and maintenance of compact treatment technology.

WCS Environmental Engineering is also a member of British Water Trade Association for the UK Water and Wastewater Industry.