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Rainwater harvesting (RWH) is the ancient practice of collecting rainwater and storing it for later use. RWH systems are comprised of a roof catchment, conveyance network, rainwater storage tank, pump, and fixtures where rainwater is utilized. Most systems also incorporate treatment technologies to improve the quality of rainwater before and/or after storage, and include provisions for periods of insufficient rainfall (a water make-up supply) and times of excessive rainfall (overflow provisions).

There is growing interest in sustainable water management that has been triggered by numerous reasons such as overpopulation, overburdened water sources and drought. Alberta is still is in the process of developing a framework to ensure the water is safely re-used for the appropriate purposes.

Permitted uses of rainwater in Alberta:

  • Sub-surface irrigation
  • Toilet and urinal flushing

Some typical re-use challenges:

  • Cross-contamination
  • Piping, storage, pumping
  • Disinfection, filtering
  • Cold weather issues

Not all stormwater is able to be used for irrigation. Pollutants in the water are often present at concentrations that would exclude stormwater for consideration to re-use due to the harmful effects it would cause to the land and the vegetation to be grown.

There are currently no water quality guidelines that pertain specifically to the use of rainwater, either nationally or in the Province of Alberta. For single-family dwellings, the quality of rainwater and the need for treatment must be evaluated in the context of connected fixtures. Connected fixtures where there is minimal contact with the rainwater do not require the same quality of water as applications where users come into direct contact with the water. Treatment needs should be determined on a case by case basis by local building or health authorities, considering the recommendations of designers and preferences of end users.

Health Canada has some information on their website on household reclaimed water. They have developed guidelines for using reclaimed water in toilet and urinal flushing.

Alberta's Municipal Affairs has created a working group dedicated to developing a framework for reclaimed water. Check out their rainwater harvesting web page. They have created a guideline for residential rainwater harvesting system.

Last updated: 1/3/2012 1:25:58 PM