Greywater Recycling Systems for Commercial Use

In commercial buildings, greywater recycling can reduce water consumption without affecting daily operations. Greywater recycling systems capture used water from showers, basins and laundry systems, treat it and supply the recycled water for non-potable (non-drinking) uses.

In this guide we’ll explain how greywater recycling systems are designed and installed, and how they can help commercial buildings to cut water use, lower bills and improve sustainability.

We’ll cover the full greywater recycling process, typical components for commercial sites, building regulations that you should be aware of and system maintenance.

Head over to our heating and plumbing services page if you want to enquire about a greywater recycling project.

What is Greywater Recycling?

Greywater is used water from showers, baths, sinks and washing machines, not to be confused with blackwater which is wastewater from toilets and kitchen sinks. Blackwater is not suitable for reuse as it contains harmful organic matter such as food particles and human waste.

In a commercial setting, greywater recycling captures used water, treats it and reuses it for non-potable uses like toilet flushing, irrigation and external cleaning.

Rainwater harvesting is a separate sustainable water management practice that involves the collection and storage of rainwater for non-potable use. Unlike greywater recycling, the water isn’t treated (as long as it is being used for non-potable purposes) and the water supply is dependent on precipitation levels and runoff infrastructure.

If you’re assessing greywater recycling options for larger buildings such as offices, public buildings, leisure centres and schools, heating and plumbing services offered by our expert team can create a solution that integrates with your pumps, controls and building management system (BMS).

What are the Benefits of Greywater Recycling?

Greywater recycling can bring environmental and economic benefits to your business. It helps the environment by reducing demand on mains water and saves money by lowering water bills.

Environmental Benefits

Reusing on-site water reduces mains water draw and the amount of wastewater entering sewage systems and treatment plants, which cuts energy use and carbon emissions.

Furthermore, it can help businesses to reach BREEAM standards (Building Research Establishment Environmental Assessment Method), which serve as a benchmark for sustainability standards, signifying the efficiency of a building.

Greywater recycling is a sustainable way of improving water efficiency and reducing your water footprint.

Offices can see savings of up to 35 litres per person daily, reducing usage by up to 70%. In leisure centres, where showers are heavily used, systems can save up to 60 litres per person per daily, cutting water use by up to 50%.

Stormsaver Sustainability Impact

Economic Benefits

In buildings with considerable toilet and shower usage (offices with gyms, sports/fitness, hotels), greywater recycling significantly lowers water bills by reducing water consumption from the mains.

Modern greywater recycling systems are designed for low maintenance with straightforward access to filters and water storage units; maintenance costs are typically limited to periodic checks to assess a system’s operations and monitor contamination levels.

Savings depend on the size of the building and the volume of water usage from greywater sources that can be reused.

How do Greywater Recycling Systems Work?

Commercial greywater systems typically follow this process:

Collection: Pipes collect greywater from showers, basins and laundry systems. Especially in older buildings, wastewater is typically mixed in drainage pipes so reconstruction of existing plumbing may be required to separate greywater from blackwater.
Pumping: Pumps transfer the water to the treatment system and a surge tank and sensors regulate the flow. In larger commercial buildings, multistage pumps are typically used to meet higher water pressure demands. These pumps have multiple rotors that help to transport the water quickly.
Treatment system: Primary filtration removes larger particulates and other debris before the water is disinfected by chemicals or undergoes ultrafiltration (a membrane filtration process that can remove small particulates). Finally, ultraviolet (UV) disinfection is a common method for removing pathogens, ensuring that the water is safe for reuse.
Storage and distribution: Filtered water sits in a labelled storage tank with backflow protection, ready for reuse. Next, multistage pumps feed toilets and other suitable outlets with the recycled greywater. Mains water is automatically supplemented if the supply of greywater is insufficient.
Controls: A control panel connected to the system’s sensors allows for easy monitoring, and for issues to be identified and resolved quickly.

Types of Greywater Recycling Systems

Commercial or Domestic

Domestic greywater recycling systems are compact, pre-packaged and often use gravity instead of pumps to distribute treated greywater.

On the other hand, commercial systems are more complex; uniquely designed for a building to match its size, layout, water use and demand. Commercial greywater recycling systems typically have these core components: separate greywater waste pipework, storage tanks, multistage pumps, filters, distribution pipework and a control panel.

Centralised or Decentralised

Greywater recycling systems in commercial buildings can either be centralised or decentralised depending on the size, layout and existing plumbing infrastructure of the building.

Centralised: The more common layout for modern commercial buildings, greywater is collected and transported to a single treatment plant. Centralised systems are more economically viable than decentralised ones and are easier to maintain.
Decentralised: Multiple treatment units are used to serve specific zones in a building. Often, it is a more suitable option for older buildings with complex plumbing infrastructure, as it doesn’t require costly modifications to existing pipework.

Greywater recycling systems are installed by constructing separate pipework for greywater collection and non-potable water distribution. Once the water usage and demands of the building have been calculated, tanks and pumps can be installed to effectively store and distribute the recycled greywater.

Our expert team of plumbing contractors can help find the best-fitting greywater recycling system for your business/building.

How Much Does It Cost?

The cost of a commercial greywater recycling system depends on many factors such as the type, size and layout of a building. Larger buildings require more pipework, pumps and storage tanks, as well as a control system that can monitor a larger system.

For older buildings such as churches, installing a greywater recycling system may be more expensive as the existing plumbing will likely need upgrading to be able to separate greywater from blackwater. In this instance, using a decentralised system could be more cost-effective.

Go to our heating and plumbing services page to get in touch with our team who can map out installation and running costs of a greywater recycling project.

Regulations and Standards for Businesses

Greywater recycling systems must prevent contamination of potable water supplies and manage hygiene. The UK Building Regulations set out the standard for drainage and waste management, and the Water Fittings Regulations outline guidance for fitting the system correctly to prevent backflow and contamination.

In addition to these regulations, BS EN 16941-2:2021 is the British Standard which specifies the principles of design, sizing, installation and maintenance of greywater recycling systems. Our expert team of plumbing contractors will help you from the design stage to the system’s installation to ensure that your greywater recycling system meets the British Standard.

Listed building consent is required to install greywater recycling systems in listed buildings. A building may be listed if it has special architectural or historical interest. Check if your building is listed, as unauthorised work is a criminal offence. Listed building consent is granted by a local planning authority.

Conclusion

Greywater recycling turns everyday flows into a dependable non-potable water supply that cuts bills, reduces waste and improves sustainability. The best results come from a thorough assessment of a building’s plumbing system and water demands, in-depth design of a greywater recycling system, careful installation and a maintenance routine that keeps quality consistent.

If you’re planning a project for an office or another type of commercial building, speak with our plumbing contractors to see how we can plan and install a greywater recycling system that boosts sustainability and reduces water bills.

Frequently Asked Questions

Check out some of our most common questions.

Where can recycled water be used?

Typical reuses are toilet flushing, irrigation for plants/garden areas, and outdoor cleaning tasks such as patio cleaning. It’s not for drinking, cooking, showering, bathing or washing clothes unless a much higher treatment process is used.

What does a greywater recycling system cost to run?

Running costs vary depending on the size of the system; most sites will see net savings, particularly where water consumption and tariffs are high. Head over to our heating and plumbing services page where our team can estimate the running cost of your greywater recycling system.

Do we need rainwater harvesting and greywater recycling?

They can operate independently or be combined to work effectively together. Successful rainwater harvesting is dependent on rainfall patterns and available roof area for runoff and collection infrastructure, while greywater recycling is driven by building occupancy and water use. Many commercial buildings use both to sustain supply and maximise reuse.