WPL HiPAF® packaged sewage treatment

Your specialist partner delivering dependable non-infrastructure and total asset value


The WPL HiPAF packaged wastewater treatment system for properties of up to 5,000 people equivalent (PE) where mains drainage is unavailable.  The range is designed to meet the highly regulated UK water utilities demanding specification and individual local environmental standards.

Each WPL HiPAF treatment plant includes a three-stage process – primary settlement, biological treatment (biozone) and final clarification, however the modular systems:

  • Can use an existing primary tank on site.
  • Below ground – WPL’s HiPAF SAF modules can be combined with a WPL humus settlement tank, lamella or conical tank depending on customer or site requirement.


Below and above ground options

Image of WPL bespoke HiPAF solution for utilities

  • Below ground – WPL HiPAF modular wastewater treatment options (up to 5000 PE) are specified with WPL MK3 UK water utility standard lids and the plant is manufactures in Glass Reinforced Plastic (GRP).
  • WPL also specifies (below ground) WPL HiPAF compact options (up to 60PE) and WPL HiPAF midi options (up to 300 PE)  to UK water utilities specification.
Read our WPL HiPAF news: WPL wins three Scottish Water framework contracts


  • Above ground – The range is adaptable  to provide an above-ground WPL HiPAF wastewater treatment system, manufactured in steel or stainless steel.

Read our bespoke WPL HiPAF case study: Yorkshire Village Installs Bespoke Steel Sewage Treatment Plant


Why you should choose the WPL HiPAF sewage treatment system:

Low installation costs and flexibility on site

  • Only a small excavation is required due to its compact design allowing flexibility of positioning on site

Low running costs

  • Significant reduction in power consumption can be achieved using variable speed drives (VSD’s), timers, instrumentation and control to deliver the lowest TOTEX solution
  • Energy saving options and chemical dosing packages can be configured to the HiPAF design for site specific requirements

Low maintenance

  • No internal mechanical or electrical moving parts within the tank therefore it requires minimal annual maintenance
  • Emptying of the tank is also not required during maintenance – the design can isolate and remove sections of the air distribution system
  • Large access lids therefore no requirement for confined space entry reducing health and safety risks
  • Access also offers ease of maintenance and process optimisation.
  • Humus and primary sludge’s are stored in one place for simple tankering operation
  • Raised air distribution pipework allows for ease of maintenance

Image of WPL MK3 lids with grating showing air distribution pipework, part of the bespoke wastewater treatment system, the WPL HiPAF

Minimal visual impact

  • Traditional below ground modular solutions do not impede views.

Variable flows and loads

  • During low flow conditions the level in the primary tank is reduced utilising forward feed air lift pumps. This creates a buffering volume that reduces the impact during high flows


  • BS1509001 CDM regulations
  • Incorporating BIM workflow principle
  • Bespoke design to ensure that the plant meets each water specification
  • Can offer a complete in-house design and specification service including a turnkey service of initial site survey, commissioning and project liaison if required.


  • Designed using the British Water Code of Practice Flows and Loads, to ensure correct sized tanks
  • Designed to BS EN 12255 – 1/15 and manufactured using BS 4994


  • Proven WPL SAF 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
  • Below ground options the 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


Each WPL HiPAF comes complete with a weatherproof, acoustically lined GRP kiosk, situated above ground. This houses the blower(s), a Form 2 control panel and air distribution manifold. Included as standard is 10m of airline, to connect the blowers to the tank.  The Form 2 control panel, automatically controls the operation of the plant.


  • N-SAF tertiary treatment option
  • Form 2 or  a Form 4 control panel is also available
  • Option of a volt free telemetry contacts on control panel
  • Duty/standby and duty standby assist blower upgrades
  • Blower kiosk cooling fan
  • Blower upgrades for long hours
  • Airline upgrades are available if the kiosk is sited further than 10m from the plant
  • Single or three phase power supplies
  • Pumped inlet flow control
  • Inverts 0.5m as standard with the option of inverts up to 1.5m with turrets
  • Lid type, orientation and colour finish options are available


WPL MK3 lids for the UK Water Utilities specification

  • Anti-slip pads on the lids
  • All lids are lockable
  • Two lids per width of the tank – lids less than 25 kilo’s to lift
  • Lockable stainless steel stays
  • Grating held in position under the lid when in the down position allows ease of access to all air distribution pipework
  • Grating when in place prevents risk of fall

Image of WPL MK3 lids showing grates to walk on, part of the bespoke wastewater treatment system

The internal sections of the plant are accessible from the top by opening the access lids, allowing for easy service, maintenance and de-sludging.

About the WPL HiPAF®

The WPL HiPAF brand name refers to High Performance Aerated Filter, which is a unique hydrodynamic flow through the biological filter bed. This helps provide even distribution across the media that is housed in the tank; ensuring strong even growth of the bacteria used in the treatment process and providing a robust stable treatment.

Feeding the biological zone is WPL’s unique airlift forward feed, maintaining a stable and even food source that enhances bacterial performance to degrade contaminants.

WPL’s robust biological treatment process is guaranteed to meet specified discharges of BOD5, ammonia and suspended solids, underpinned by over 25 years of experience and empirical data.