Building Magazine


New provincial guidelines and training seminars promote water conservation with new rainwater harvesting systems

Water conservation is one of many issues at the forefront of efforts to improve management of water resources and reduce municipal costs associated with water treatment and distribution. One way of conserving water is with Rainwater Harvesting (RWH), the ancient practice of collecting rainwater and storing it for later use. Research conducted by the Toronto and Region Conservation Authority (TRCA), through the Sustainable Technologies Evaluation Program (STEP), showed that RWH systems in commercial and industrial buildings can lower annual water use for toilet flushing and grounds irrigation by between 59 and 76 per cent, while reducing stormwater runoff from roofs by up to 42 per cent. In a study of rainwater harvesting in suburban homes, the University of Guelph reported savings of 60,000 to 70,000 litres of water annually – reducing a typical family’s water bill by 30-40 per cent. Even though these numbers are astounding, adopting this water-saving approach to supply water for flushing toilets and urinals, or for use in landscape irrigation, has largely been neglected in Canada due to a lack of knowledge about these systems and how to install them.

The Ontario Guidelines for Residential Rainwater Harvesting Systems have been published to help builders, engineers, contractors, municipalities, community groups, and DIY homeowners implement rainwater harvesting projects. These guidelines, the first of their kind in the province, were developed over the course of a four-year collaborative process, involving researchers from the University of Guelph (under the direction of Dr. Khosrow Farahbakhsh), the Ontario Ministry of Municipal Affairs and Housing, Connect the Drops and members of the Province’s private sector.  It draws upon the experience and “lessons learned” from Ontario’s experts in the field – ensuring that issues that are uniquely Canadian, like building RWH systems to handle Canada’s cold weather climate, are covered.

“With the publication of the Ontario Guidelines for Residential Rainwater Harvesting Systems, Ontario’s practitioners will have the guidance and tools they need to make our Province a leader in implementing this innovative approach to water conservation and stormwater management,” said Chris Despins, president, Connect the Drops.

The guidelines cover a variety of topics, including: sizing rainwater storage tanks, installation of rainwater (non-potable water) plumbing, rainwater treatment, as well as how to design RWH systems to operate during dry periods and handle overflows from the tank.  The document focuses upon residential applications, but is also a valuable tool to assist with the design, installation and management of RWH systems in ICI (industrial, commercial and institutional) buildings.  

To help promote rainwater harvesting throughout Ontario the TRCA is partnering with Connect the Drops to deliver a series of rainwater harvesting training seminars based on the new Guidelines. The first one-day training course will be offered on February 9, 2011 and will focus upon the regulatory and technical aspects of RWH systems for both residential and ICI buildings. The course is targeted at contractors, builders, designers, architects, regulators, or anyone interested in learning about the design, installation and management of RWH systems.  

Participants attending the training seminars will be provided with a copy of the Ontario Guidelines, and receive step-by-step guidance on the material in the guidelines, and how to use it to implement rainwater harvesting projects.  The seminars will include a variety of teaching formats, including instructor-led instruction, group exercises, and includes a 45 minute design charette.

“The training course is the first of its kind in the Province and will provide a great opportunity for those in the building industry to learn about this exciting technology.  Participants will have a chance to get their questions answered by industry experts, will receive a copy of the design tool software and will leave the workshop with the knowledge and confidence to promote this technology on future projects” said Tim Van Seters, Manager, Sustainable Technologies Evaluation Program, TRCA.

The Ontario Guidelines for Residential Rainwater Harvesting Systems is available for download at and TRCA’s STEP website:

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