As a society, we persist in the delusion of endless natural abundance, while remaining blind to the squandering of many of the resources that surround us. Our systems rely on high-value inputs that generate “low-value” outputs – which are usually labeled as “waste” and become a disposal problem rather than an opportunity.
Fortunately, every shortage gives us an opportunity to re-examine the value of these wasted resources. Now that the Comox Valley Regional District (and soon, likely, many other coastal communities) has moved to Stage Two water restrictions, it’s a good time to talk about greywater recovery and reuse.
Greywater reuse is the next frontier for residential plumbing. It was formally introduced in the 2012 version of the BC Plumbing Code but still remains far from standard practice. A Manual of Composting Toilets and Greywater Practice, currently being developed by the Ministry of Health for publication in later 2015, will hopefully make this more mainstream. In the meantime, here is a primer:
‘Greywater comes in two categories: “light grey” water comes from bathing, showering and laundry, and is suitable for re-use with minimal treatment (primarily filtration);
“dark grey” water comes from preparation of food and drink and dishwashing. Because of its propensity to be high in organic material and fats etc, it is only reusable with treatment and is generally better dealt with in the “blackwater” waste stream.’
The obvious uses for greywater are 1) toilet flushing, 2) watering of gardens, trees and lawns and, ultimately, 3) replenishing groundwater. Appropriate treatment is very important and a range of systems exist – from highly-engineered (and pricey) proprietary units that filter greywater for reuse within the home, to simple owner-built systems that usually rely more on natural processes to render it safe for use. One great example is the one used at Eco-Sense, the Victoria home of Ann and Gord Baird. This system combines the use of organic material and worms as biofilters to pre-treat greywater (see photo), with the organic residue eventually ending up in the garden.
Other systems include constructed wetlands in which water is filtered through reed beds before it returns to aquifers or is used for landscape irrigation or flush toilets. The new Code mandates “purple plumbing”, which can be installed during home renovation or construction. This distinguishes greywater from other wastewater streams at source, and can send it directly to a treatment system and/or outdoors for irrigation. The purple colour is a universally-recognized indicator that the water is unpotable.
Our biggest obstacle to the widespread adoption of these initiatives is a lack of knowledge. We hope that the forthcoming manual by the Province will help to ameliorate this. In the meantime, let’s do what we can to conserve and reuse our precious water.