Fully buried new-build greywater diversion system
GreyFlow™ PRO | 2-Stage | Below Ground
A configurable below-ground GreyFlow™ diversion system for eligible household greywater, designed so the underground housing can be installed during the build and the selected filtration and pump package fitted at completion.
GreyFlow™ PRO is the larger fully buried GreyFlow™ new-build pathway, using a 100mm greywater inlet and overflow, selectable manual or automatic-backflush filtration, and 100W, 300W or 400W pump options to suit different subsurface irrigation requirements.
Installation 2-Stage
Pre-lay housing + finishing kit
Plumbing 100mm
Greywater inlet and overflow
Filtration Manual / Auto
Selectable cleaning pathway
Pump options 100 / 300 / 400W
Match the irrigation design
Product background
Build the greywater infrastructure in now — complete the working system later
GreyFlow™ PRO 2-Stage is designed around the construction sequence of a new home.
The below-ground access pit can be installed while the drainage and underground services are being formed. The filtration, pump and control components are then fitted later as the building approaches completion.
This avoids needing to install the complete operating equipment early in the build while still allowing the dedicated greywater plumbing and below-ground housing to be established at the correct construction stage.
Why two-stage? Installing the access pit during the building stage is substantially easier than trying to introduce the same below-ground infrastructure after the house, paving and landscaping have been completed.
Configure your system above
One complete product — three required selections
WCTNZ® supplies the GreyFlow™ PRO as one configurable system. Use the product options above to select the physical components required for your installation.
1. Housing
GreyFlow™ PRO below-ground housing / Builder’s Kit
The main access pit is installed during the new-build pre-lay stage and receives the dedicated greywater inlet and overflow plumbing.
2. Filtration + pump
Choose Manual Clean or Automatic Backflush, then select 100W, 300W or 400W.
This is the Stage 2 finishing package installed as the building reaches completion.
3. Access cover
Select the cover to match the expected surface loading.
Available pathways include Non-Trafficable, Pedestrian Trafficable and Class C Trafficable access-cover options.
The individual housing, finishing-kit and cover components can remain separately stock-managed within the WCTNZ® product system even though they are purchased together here as one configured GreyFlow™ PRO package.
Installation pathway
Install, finish and distribute
Stage 1 Install the Builder’s Kit The GreyFlow™ PRO below-ground access pit is installed during the new-build pre-lay stage with the dedicated 100mm greywater inlet and overflow plumbing.
Stage 2 Fit the finishing package At building completion, the selected filters, pump and associated manual-clean or automatic-backflush equipment are installed into the prepared housing.
Stage 3 Connect the irrigation field Filtered greywater is pumped into the site-designed subsurface land-application system, with distribution sized to the expected water volume, levels and available irrigation area.
How it works
Filter suitable greywater, pump it out and reuse it below the surface
- Eligible household greywater enters the below-ground PRO housing through the dedicated 100mm greywater line.
- Greywater passes through the selected filtration pathway before entering the pump section.
- A float-controlled discharge pump sends filtered greywater to the subsurface irrigation system when the operating level is reached.
- The overflow pathway remains available so incoming water has a controlled route when the greywater-reuse system is not accepting or pumping the flow.
- The irrigation network distributes the diverted greywater below the ground surface through the designed land-application area.
Choose the filtration mode
Manual Clean or Automatic Backflush
Manual Clean
The simpler finishing-kit pathway uses physical filters together with the selected float-controlled discharge pump.
The filters require regular owner or service access for cleaning as system loading and site conditions require.
Choose Manual Clean where straightforward servicing is acceptable and automatic filter backflushing is not required.
Automatic Backflush
The automatic configuration adds a controller, air-blower cleaning system, additional float control and the fittings required for automatic filter backflushing.
The manufacturer operating sequence activates a backflush cycle after a set number of pump-out cycles to clean the filter pathway automatically.
Choose Automatic Backflush where lower routine filter intervention and a more automated operating pathway are preferred.
Automatic backflushing reduces routine filter-cleaning intervention but does not remove the need for periodic inspection and scheduled system maintenance.
Choose the pump
Match pump performance to the site
Pump selection depends on the elevation of the irrigation area, pipework, required flow and complete land-application design.
100W
6.5m
70 L/min
For lower-head applications, typically where the irrigation area is at the same or a lower level.
300W
8m
180 L/min
For greater flow and moderate lift; manufacturer guidance positions this for same-level irrigation or approximately 3m higher.
400W
21m
180 L/min
Higher-head option. Manufacturer selection material positions it for irrigation areas up to approximately 12m higher and specifies it for the stated XR subsurface lawn-dripline pathway.
Not sure which pump? Do not choose only from the vertical height difference. Pipe length, friction losses, distribution layout and irrigation design also affect the required pump duty. WCTNZ® can help review the application.
System fit
Designed for domestic new-build greywater reuse
Product type
Greywater Diversion Device / below-ground pumped greywater-reuse system.
Application
Domestic new-build installations with a dedicated greywater plumbing pathway.
Manufacturer GDD range
Up to 1,000 litres per day within the Greywater Diversion Device category.
Typical sources
Shower, bathroom basin and laundry greywater connected to the dedicated greywater line.
Inlet / overflow
100mm inlet and 100mm overflow.
Installation
Fully buried / below-ground with adjustable installation height.
Access opening
600mm access-cover pathway with selectable cover loading.
Filtration
Manual-clean filtration or automatic air-backflush filtration.
Pump options
100W, 300W or 400W.
Reuse pathway
Subsurface / sub-strata greywater land application.
Certification
GreyFlow™ GDD range identified by AWWS under WaterMark WMTS 460:2016.
Whole-of-house greywater
“Whole-of-house” does not mean every wastewater stream
The PRO uses a large 100mm dedicated greywater plumbing connection and is suited to collecting multiple eligible household greywater sources through one system.
Kitchen wastewater: the GreyFlow™ PRO manufacturer manual specifically excludes kitchen water from this GDD configuration.
Kitchen wastewater should therefore remain on its appropriate wastewater pathway unless a separately designed and approved treatment or management solution is being used.
Toilet waste and other blackwater remain completely separate from the GreyFlow™ PRO greywater system.
Diversion, not treatment
GreyFlow™ PRO is a Greywater Diversion Device pathway
The PRO filters and diverts eligible greywater for appropriate subsurface reuse. It is not the same as a Greywater Treatment System that produces treated water for broader non-potable reuse.
If your project requires treated greywater for applications such as toilet flushing, broader irrigation options or commercial reuse, the project should be considered against the appropriate GreyFlow™ treatment-system pathway rather than assuming the PRO diversion system performs that function.
Subsurface distribution
The irrigation field is part of the complete system design
GreyFlow™ PRO does not end at the pump outlet. The receiving subsurface land-application area needs to be sized and laid out for the expected greywater volume, soil, available garden area, site levels and selected pump.
- GreyFlow™ high-flow dripline can be used to distribute diverted greywater below the surface.
- Feeder pipe, flushing points and air-release details form part of the complete irrigation pathway.
- A GreyFlow™ Rotor can divide the discharge into multiple stations where the irrigation design requires a larger distribution area.
- The manufacturer documentation provides for multi-station distribution through up to six rotor outlets.
- Final land-application design must suit the actual site and applicable local requirements.
Access cover selection
Match the cover to where the pit will be installed
The access cover is a required product option because the correct cover depends on the expected surface loading at the installation position.
Non-Trafficable
For service-access positions without pedestrian or vehicle loading.
Pedestrian Trafficable
For locations where pedestrian surface loading is expected.
Class C Trafficable
For higher surface-loading applications where the surrounding installation and access structure are designed accordingly.
Pit extension
A GreyFlow™ PRO pit extension is available where additional access height is required.
Maintenance
Keep the filtration, pump and irrigation pathway serviceable
Greywater systems handle real household wastewater and need ongoing inspection and maintenance to retain reliable performance.
- Manual-clean systems require regular physical filter cleaning according to use and site conditions.
- Automatic-backflush systems automate routine filter-cleaning cycles but still require scheduled inspection and maintenance.
- The tank, pump, float controls and filters should remain accessible for servicing.
- The irrigation network should be flushed and checked as part of ongoing system maintenance.
- Greywater-contact hygiene procedures should be followed during inspection and servicing.
WCTNZ® guidance
Choose the complete greywater pathway, not just the pump
Greywater system selection depends on the source water, household use, site levels, pipework, soil, available land-application area and the outcome you want from the system.
WCTNZ® can help determine whether GreyFlow™ PRO, another GreyFlow™ diversion device, or a full greywater treatment pathway is the better match for the project.
WCTNZ® is the official distributor of GreyFlow™ greywater systems in the Realm of New Zealand , including New Zealand, the Cook Islands, Niue, Tokelau and the Ross Dependency.
