WPL HiPAF® compact – 1 to 60 PE

Meets stringent standards stipulated by the Environmental Agency


The WPL HiPAF Compact (HPC) offers sewage treatment for properties of 1 – 60 people equivalent where mains drainage is unavailable.

Using no chemicals, the WPL HiPAF range meets stringent European environmental discharge consent standards and is regularly specified by UK water utilities. This makes the range the preferred choice for sensitive locations such as a Sites of Special Scientific Interest (SSSI) such as:

  • Nature reserve
  • Fisheries
  • Salmon river
  • Close proximity to water extraction (well)

UK designed and manufactured in the glass reinforced plastic (GRP) – installed above and below ground.


Why you should choose the WPL HiPAF Compact (HPC):

 Discreet and low cost installation

  • Only a small excavation is required due to its compact design
  • Easily transported to the continent

Minimal visual impact

  • Does not impede views when installed below ground

Low running cost and maintenance

  • The unique design has no internal mechanical moving parts within the tank making it economical to run
  • Emptying of the tank is also not required during maintenance of air distribution system
  • Safe, clean, accessible air diffuser system with large access lid for easy maintenance
  • Humus and primary sludge are stored in one place for simple tankering operation
  • Can use an eco-panel and blowers that reduce power consumption
  • Robust operation and stand-by facility

 Variable flows and loads

  • The unique design of the flow balancing in the primary tank means it can cope with variable flows and loads making it ideal for caravan sites and other seasonal venues

No odours

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


  • CE marked, fully type tested and certificated in accordance with the mandatory European standard BS EN12566-3, and meets all current legislation under the Environmental Permitting Programme
  • Fully compliant with UK Building Regulations and Environment Agency recommendations
  • Designed using the British Water Code of Practice Flows and Loads, to ensure correct sized tanks


  • Proven WPL technology based on over 25 years empirical data
  • Unique internal circulation system leads to increased process performance
  • Use of high quality blowers and pumps underpins reliability of plant
  • GRP is UV stabilised with an external gel coat finish which extends the asset life to 25 years
  • Plants and kiosks are produced in a quality controlled environment at the WPL factory

Typical uses for the WPL HiPAF compact sewage treatment plant include:

  • Domestic housing
  • Commercial buildings and offices
  • Stately homes and country estates
  • Small hotels and bed and breakfasts
  • Small retail such as farm shops
  • Small villages, rural communities and housing associations
  • Specified by the highly regulated UK water utilities

Image of a WPL HiPAF Compact ultra-performance plant, compact sewage and wastewater treatment

Technical Specification of the WPL HiPAF compact (HPC) sewage treatment plant:


wpl-hipaf-compact-technical-table-sewage-treatment-not-connected -to-mains-drainage

The table is an indicative guide only; all applications are specified to comply with the British Water Code of Practice for Flows and Loads.  For further advice please contact our experienced technical sales team.

WPL HiPAF diagram showing the treatment process


Image of HiPAF Compact process showing sewage and 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


The WPL HiPAF treatment process


  • Primary settlement is in accordance with BS EN12255-3, giving the required hydraulic retention time and ensuring that 30% of the BOD will settle out in the primary tank.
  • 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 Limited’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.


  • 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.


  • 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.