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Quick explanation

  1. Gravity transports greywater to the system.
  2. Preliminary filtration removes large debris (like hair).
  3. Greywater enters biological treatment tank for oxygenation.
  4. Oxygenation helps the growth of beneficial bacteria.
  5. Fine hollow fibers filter out bacteria and viruses.
  6. Treated greywater is stored in clean tank for distribution.

Detailed explanation

Pre Filtration 

Greywater is transported from collection points within bathrooms across the building via a separate network of pipes. Not only does this eliminate the potential for cross-contamination, but it also allows the possibility of heat exchange technologies to recover heat from the waste greywater. Collection occurs via gravity. 

Preliminary filtration removes undissolved contaminants from the greywater supply including hair and textile fibres. On Stormsaver Systems, preliminary filtration is supplied with a high-pressure backwash feature which supplies processed greywater to provide self-cleaning to the preliminary filtration device. 

Biological Treatment

Greywater then enters the biological treatment tank.

The biological treatment process introduces aeration to naturally degrade organic contaminants such as shower gels and foam. The biological treatment tank also contains growth bodies to separate biofilm from the greywater. Growth bodies are designed to increase the surface area within the tank for biofilm to attach. 


Aeration assists suspended solids in settling on the base of the treatment tank via sedimentation. These are removed via an efficient sludge pump. 


Greywater is then processed through ultrafiltration. Ultrafiltration processes greywater through hollow fibres to separate any remaining microbiological particles such as bacteria and viruses (rated to 0.02 microns). The automatic self-cleaning process includes a short backwash of the ultrafiltration device to remove contaminants for the best possible water quality. The control panel fully automates this process for complete peace of mind. 


Treated greywater is then transferred a separate clean water tank for storage until required. A low nutrient load from the biological treatment process and removal of solid particles ensures greywater can be stored for extended periods. 

Mains water topup

Where limited greywater is available, an automatic mains water backup will continue to provide a water supply to outlets. The mains water backup is achieved through a WRAS-compliant air gap in the clean water tank. The process is fully automated by our control panel. 

Water Availability

Water scarcity is a growing problem for the UK.

Population growth, continued expansion of the built environment, and climate change are causing significant challenges for water supplies. The UK Environment Agency has estimated that an additional 5 billion litres per day will be required to meet demands in the next 25 years.

Greywater Recycling can help us to solve these challenges by providing a sustainable water supply for non-potable use in residential buildings.

Discharge Rates

Wastewater accounts for a significant proportion of total water discharge from a building. Once water is discharged, it enters the drainage network.

Much of the UK sewer infrastructure transports wastewater and stormwater together causing frequent overflows into surrounding water courses.

Greywater Recycling can effectively reduce wastewater discharge rates by facilitating the reuse of bathroom greywater.

Greywater Recycling can provide a non-potable water supply for many common water uses within residential settings. These cover…

  • Toilet flushing
  • Vehicle washing facilities
  • Laundry
  • Cooling
  • Living wall irrigation

Greywater Recycling is well suited to high-density residential properties. Water use in residential settings is difficult to reduce due to the requirement for consumer habit changes. Relying on Greywater Recycling removes the need for behaviour changes and contributes towards reduced litres per person per day figures (LPPPD).  The below buildings are well suited to Communal Greywater Recycling.

  • Apartments
  • Student accommodation
  • Hotels

Our Communal System Types

Communal Greywater Recycling Systems are sized specifically for individual projects. Several factors inform the design of these systems, including collection yield, demand for water, and occupancy.

Our team of specialists can assist with your sizing requirements. Alternatively, you can discover our system types below.

 a diagram of a greywater recycling system in a hotel building

Standalone Solutions

  • NSF certified to provide high-quality water supplies.
  • Incorporates ultrafiltration (0.05 microns) to remove bacteria.
  • Houses ultrafiltation within the treatment tank for a low footprint.
  • Intelligent self-cleaning of filters.
  • Automatic chemical dosing for cleaning associated pipework.
  • Optional IoT removing monitoring via a desktop or mobile.
  • Smart controls to allow for flexible shut-down periods.

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 a combined greywater recycling rainwater harvesting and attenuation diagram

Combined Solutions

  • Greywater Recycling can be combined with Rainwater Harvesting and Active Attenuation.
  • Increase the volume of recycled water supply by combining technologies.
  • One intelligent system to meet all non-potable requirements.
  • Commonly used for areas of water neutrality and densely populated regions.
  • Supplied in above or below-ground arrangements, including blue roofs.
  • Optional IoT monitoring.

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Technical Features

IOT Monitoring: Access real-time information system health, faults, and receive notifications on service and maintenance requirements.

High-Efficiency Ultrafiltration: Removal of microbiological contaminants down to 0.02 microns, providing a safe, clean water supply.

Self-Cleaning Cycles: Automatic backwashing of filters, prolonging lifespan and reducing maintenance requirements.

Variable Controls: Ease of start-up and shutdown of the system for building closure periods.

Autonomous Chemical Dosing: Removal of biofilm from associated pipework via smart chemical cleaning, preventing blockages and disruption.

High-Pressure Cleaning: Debris from pre-tank filters are removed via a high-pressure backwash nozzle, removing debris and increasing system efficiency.

Further Information

Communal Greywater Recycling takes advantage of a single, commercial-style system for residential properties to collect and reuse bathroom wastewater for the provision of a non-potable water supply. 

  • Remove ownership and maintenance responsibilities from the homeowner to a management organisation.
  • Remove internal components from homes, assisting with reduced risk of cross-contamination between the greywater and mains water supplies.
  • Prevent homeowners from switching the system off due to a lack of knowledge.
  • Utilise commercial-grade components for an extended lifespan.
  • Mitigate the need for consumer behaviour changes in water usage by supplying them with greywater.

Why Choose Stormsaver?

 An illustrative image showing a greywater recycling filter

Our Added Value Options

Looking for UV disinfection or installation services on your new greywater system? Our added value options give you access to best-practice approaches. Learn more here. 

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Constructionline Gold Member CHAS Accredited UK Rainwater Harvesting Association Member Safecontractor Approved Waterwise Affiliate UK Business Awards Winner 2022