Water recycling: A step to better water stewardship and public health

My children were angry at me. It was another scorching summer day and the “waterpark” Dad built in the backyard was not operational due to water restrictions. Incredibly, in rainy Vancouver, a poor winter snowfall combined with the record sunny summer we experienced last year resulted in a moratorium on running the hose over the playhouse slide. The kids were dying to cool off, which is better than how the garden tomatoes felt; they were just dying.

As my children and tomatoes continued to wilt I chatted with my neighbor and learned that Vancouver restricts the outdoor use of only treated drinking water.[1] My neighbor has a rainwater tank. Now I do too, and I am ready for another summer.

Water restrictions are not always headline news, but they do point to a growing issue in BC and throughout the world. To be sure, drought has been part of the earth’s climate repertoire for millennia, but current projections call for increased frequency of and more widespread occurrence of water shortages as global temperatures rise.[2]

The human health implications of water scarcity are already upon us and are likely to be further exacerbated as water supplies become more precarious. Water scarcity directly threatens agricultural production, food security, and the effectiveness of sanitation systems. Also troubling are the geopolitical implications of diminishing access to water. The World Bank warns of the prospects for economic decline, increased poverty, and international conflict.[3]

Though there are many facets to prudent water management, one option is to recycle greywater and rainwater. Greywater is the household wastewater from bathtubs, showers, sinks, dishwashers, and washing machines. Water from toilets and urinals is considered blackwater and is not suitable to be recycled. Water from kitchen sinks and dishwashers, which contains food waste, may be considered grey or black depending on the jurisdiction.[3] Rainwater can be harvested from roofs or through other collection methods.[3]

It is estimated that reusing greywater can save up to 60% of household water,[4] and there are many ways to reuse water (e.g., watering gardens and lawns, or flushing toilets and urinals), but regulations around reusing water vary across jurisdictions.

In BC regulations have included provisions for the use of reclaimed water since 1999. Wastewater in BC is already being reused in toilet/urinal flushing, landscape watering, playground use, green-roof irrigation, golf course irrigation, and forage crop irrigation. The BC government has also updated the Building Code to allow water utility providers to distribute nonpotable water and to allow nonpotable distribution systems to be installed in buildings.[3] Currently, the BC Ministry of Health is drafting a manual for greywater use in composting toilets.[5]

Using recycled water to flush our toilets and to water our lawns and gardens can benefit the environment by reducing the draw on drinking water, improving plant growth and soil maintenance, recharging local groundwater, and decreasing the load on sewage and treatment infrastructure. To go a step further, some systems can even extract the heat from washing machine and bath effluent for use elsewhere in the home.

On the other hand, the use of reclaimed water may carry human health risks, although the danger is thought to be low.[6] For example, water from bathing may carry potentially pathogenic microorganisms, and water from kitchen sinks or dishwashers may contain food waste and chemicals.[7] Moreover, some chemicals contained in greywater can adversely affect plants.[7] To mitigate risks to human health and agriculture, systems are typically used to prevent direct human exposure or to divert unwanted waste and chemicals.

In BC there are still opportunities to enhance existing regulations to balance water stewardship with public health, including more comprehensive Ministry of Health policies and regulations for reusing different types of water, and municipal bylaws on plumbing code reuse provisions.[3] More broadly, greater alignment between environmental, health, and municipal policies and regulations can minimize human health risks associated with reusing water.

At home, my rainwater barrel is standing ready and my garden is looking good.

But my kids are still angry at me. They hate tomatoes.
—Lloyd Oppel, MD

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This article is the opinion of the Council on Health Promotion and has not been peer reviewed by the BCMJ Editorial Board.

References

1.    City of Vancouver. About the watering restrictions. Accessed 18 April 2016. http://vancouver.ca/home-property-development/about-the-watering-restrictions.aspx.

2.    Alavian V, Qaddumi HM, Dickson E, et al. Water and climate change: Understanding the risks and making climate-smart investment decisions. The World Bank, 2009. Accessed 21 April 2016. http://documents.worldbank.org/curated/en/2009/11/11717870/water-climate-change-understanding-risks-making-climate-smart-investment-decisions.

3.    UBC News. UBC expert calls for better water recycling in BC. Accessed 21 April 2016. http://news.ubc.ca/2015/08/31/ubc-expert-calls-for-better-water-recycling-in-b-c/.

4.    US Department of Energy: Energy Efficiency and Renewable Energy. Guide to home water efficiency (2010). Accessed 21 April 2016. http://publications.usa.gov/USAPubs.php?PubID=331.

5.    Government of British Columbia. Draft provincial composting toilet manual. Accessed 21 April 2016. www2.gov.bc.ca/gov/content/environment/waste-management/sewage/onsite-sewage-systems/draft-composting-toilets-manual.

6.    Busgang A, Friedler E, Ovadia O, et al. Epidemiological study for the assessment of health risks associated with graywater reuse for irrigation in arid regions. Sci Total Environ 2015;538:230-239.

7.    State Government of Victoria, Australia. Greywater – recycling water at home Accessed 15 April 2016. www.betterhealth.vic.gov.au/health/healthyliving/greywater-recycling-water-at-home.