Home greywater reuse systems collect greywater from household showers and baths, purify the greywater collected using chlorine, and utilize the treated greywater to flush toilets within the home. Toilet flushing represents about 30 per cent of daily water use in the home. Using reclaimed greywater from showers and baths eliminates the use of potable water for toilet flushing, resulting in significant annual water and wastewater cost savings.To help homeowners understand greywater reuse system design and construction requirements, the City of Guelph designed a Greywater Reuse System Buyer’s Guide.
A limited number of incentives are available for existing homeowners and residents, purchasing new homes, to install an approved greywater reuse system. Please note: Available rebates will be provided on a first come first serve basis.
How does a residential greywater reuse system work?
Water use in a standard home
In a standard home, water from the municipal system is fed to each appliance and fixture. The greywater or wastewater produced from each appliance or fixture is then sent directly to the sanitary sewer as shown in the diagram below.
Water use in a home with a greywater reuse system
Homes that feature a greywater resuse system collect greywater from showers, and filter and purify the greywater to be used in the home where potable water (drinking water quality) is not required, such as toilet flushing. The diagram below illustrates water use in a home with a greywater reuse system.
Greywater Field Test Program
In May of 2009 the City of Guelph initiated the Greywater Field Test. This innovative study aimed to assess the feasibility of large scale adoption of centralized home based greywater reuse technologies in continuation of the City’s water conservation objectives. As part of the study a home installation target of 30 greywater reuse systems was established with installations taking place within new and existing single family homes in the Guelph community. To assess the feasibility of these systems five core areas of study were chosen by the project team. These core areas include:
- System Operation and Performance
- Homeowner Satisfaction
- Household Water Use Monitoring
- Municipal Management Frameworks and Required Support Networks
- Premise Isolation Device Requirements
Greywater Field Test Team
The Greywater Field Test project Team is comprised of various local community stakeholders including
- Fusion Homes
- Reid’s Heritage Homes
- Evolve Builders Group Inc.
- Veritec Consulting Inc.
- School of Engineering
Federation of Canadian Municipalities Green Municipal Fund
This field test was carried out with assistance from the Green Municipal Fund, a Fund financed by the Government of Canada and administered by the Federation of Canadian Municipalities. The City of Guelph would like to sincerely thank FCM for their support of this initiative.
Greywater Field Test
- Appendix A: York Trunk Sewer and Paisley-Clythe Feedermain Municipal Class Environmental Assessment
- Appendix B: Water Savings Monitoring Data
- Appendix C: Treated Greywater Testing Results by Parameter (all participants)
- Appendix D: Preliminary Lifecycle Assessment (PLCA)
- Appendix E: Municipal Management
- Appendix F: Social Feedback Monitoring and Acceptance Data
For more Information
Wayne Galliher, A.Sc.T.
Water Conservation Project Manager
519-822-1260 extension 2106
Frequently asked questions about greywater
What is greywater?
Greywater is wastewater generated from household sources such as clothes washing, bathing and showering. This wastewater is still of a high quality in comparison to other sources of wastewater generated within the home. Greywater Reuse systems collect water from daily showers and baths in the home and recycle that water for use in toilet flushing, which can reduce household water use by up to 30%.
What can greywater be used for in the home?
The Ontario Building Code allows for the use of treated greywater for only toilet/urinal flushing and the priming of floor drains within the home.
**Note** Water treated through residential greywater reuse systems does not meet the provincial drinking water quality standards and should not be consumed under any circumstance
How can I participate in the greywater reuse rebate program?
As part of this exciting initiative, a rebate of $1000 is provided toward the installation of approved greywater reuse systems within new and existing homes.
Buying a newly built home?
Why not consider whole-home water efficiency with Blue Built Home – a water efficiency standards and rebate program. Blue Built Homes offer water-efficient fixtures, appliances and systems (including greywater reuse) installed before you move in that will save you water and money and provide a rebate once you take possession! Ask your builder for more information or visit bluebuilthome.ca/guelph.
What is required maintenance for a home greywater system?
Regular maintenance is required to ensure continued operation of a home’s greywater system. Maintenance includes cleaning the system’s filter, adding chlorine pucks, and cleaning the system’s greywater collection tank. The maintenance schedule below indicates the frequency of each task:
Typical Greywater Reuse System Maintenance Schedule
- Clean system filter monthly
- Add chlorine puck monthly
- Clean collection tank annually
Note: The maintenance requirements identify general maintenance practices for residential greywater reuse systems. Homeowners are also encouraged to reference the owner’s manual for their specific greywater reuse system to identify further recommended practices from the manufacturer.
What can happen if required system maintenance is not completed?
It is important that the required maintenance be completed in accordance with the recommendations of the system manufacturer. Failure to follow the maintenance requirements include:
Clogged system filter: This will limit raw greywater from entering the system. With no new greywater entering the system, potable drinking water would be used to fill the system. This would increase water use in the home and negate water and wastewater savings.
Bacterial growth:Chlorine is required to purify water collected and limit bacterial growth within the greywater source. Failing to add or replace the chlorine puck can lead to bacterial growth in the greywater collected. Bacterial growth may result in discolouration and odour to the greywater collected, as well as the formation of biofilm in the greywater storage tank. Failing to clean the system’s collection tank on an annual basis can also lead to bacterial growth.
Are there any health concerns associated with home greywater reuse?
Potential health concerns associated with residential greywater reuse centre primarily around the direct consumption of residential greywater. Direct consumption may occur through the wrongful cross connection of home greywater supply lines with home drinking water supply also present in the home. In preventing potential cross connections, all water service lines carrying greywater in the home are required to be fully marked during installation with “non-potable’ labelling. This labelling serves as an indicator that water carried through these lines is not of drinking water quality and not suitable for human consumption.
It is important to note that water treated through residential greywater reuse systems does not meet the provincial drinking water quality standards and should not be consumed under any circumstance.
Are there any cleaning products that should be avoided due to the chlorine in the greywater tank?
It is advisable to avoid bleach or products that should not be mixed with chlorine. Since typical chlorine levels in the greywater system are similar to the City’s potable water chlorine level, generating toxic gases from cleaning products is very slim. If there ever was a reaction, the greywater tank is plumbed with a vent so that the gases would escape out through the vent and not into the house. For safety, do not clean your bathtubs or showers with the filter cap on the greywater system removed. If still concerned, close the ‘greywater in’ valve prior to cleaning so that all chemicals bypass the greywater tank.
Who can I contact if there is a mechanical issue with the greywater system?
For mechanical issues, please contact your greywater system manufacturer.
Where can I obtain more chlorine pucks?
Chlorine pucks may be obtained through a pool supply retailer or your greywater system manufacturer.
Where can I obtain more filters?
Filters can be obtained through your greywater manufacturer.