Greenovation+

Vol. 3 2013 Graywater

We once believed that water was an endless resource, where the term “water conservation” was rarely discussed. Today that is a thing of the past, and in order to preserve the water for future generations we must do our part and conserve this precious resource. In North America, the dangers of drought can become quite serious, leaving a short supply of water for residents and businesses. By using graywater where possible instead of fresh water, we can all help decrease the demand and ensure that there is enough water for us in the future[i].

What Is Graywater And How Does It Work?

Graywater is a term used most often to describe water from washroom sinks, showers, baths, and washing machines. In fact, approximately 74% of water used in homes can become graywater[ii]. Once the water is filtered, pressurized and pumped, it can be used in household exterior applications, including car washing and irrigation to gardens[iii].

graywater house

 

Water reuse is not a new process for several states and countries. In the late 80’s, Florida became a national leader; and within Europe, Germany became a leader in encouraging rainwater catchment systems[v].

When Gray Turns Black

However, not all water that comes out of sinks, showers, baths and washing machines may be recycled into graywater. In order for water to become graywater, it cannot contain high amounts of sodium, non-biodegradable and toxic soaps, grease, human waste, phosphates or bleach – all of which can harm plant life. If any of these substances listed above are found in water (in large quantities), the term will become “blackwater”.

“Blackwater” is also referred to as standing graywater, untreated, for more than 24 hrs due to the high amounts of bacteria contained within the water[vi].

 Rainwater Harvesting

 

BRAE Brae Rainwater Harvesting

Rainwater harvesting works by collecting rainwater in a catchment area, which is then directed into filtration units. These filtration units consist of levels of sediment filters and ultra-violet light (eliminate bacteria). The result of this is high-quality reclaimed water, which can then be used for water for livestock, irrigation, flushing toilets, vehicle wash and laundry, and also to replenish ground water levels[vii].

Benefits[viii]

  • Rainwater is free; the only cost is for collection and use.
  • Lessens the demand on the municipal water supply.
  • Saves money on utility bills.
  • Provides effective stormwater runoff management by diminishing flooding, erosion and reducing the flow to stormwater drains.
  • Stored water can be used for flushing toilets, urinals, car washing, cooling tower water make-up and landscaping
  • Beneficial for irrigation, and plants thrive because stored rainwater is pH neutral and free from pollutants as well as salts, minerals, and other natural and manmade contaminants.
  • Harvested rainwater can meet most non-potable water demands, which comprises of about 89% of all water use in a typical office building.
  • Helps achieve LEED® credits under Water Use Reduction, Water Efficient Landscaping, and Storm water Management.

 

Rainwater Harvesting Case Study

AdvancED, a school-accrediting agency, was eager to partake in an environmentally conscious activity of incorporating rainwater harvesting at their office. Rainwater is collected from their roof, which goes into an underground tank near the base of the building, and overflow from the tank is drawn into the stormwater drainage system. Rainwater from AdvancED’s roof is directed back into the building for use, and through an energy conservation feature. This feature sends water mist to the evaporative coolers, which increases the efficiency of the building’s coolers[ix].

One challenge we face is that rainwater harvesting and graywater practices are not acceptable everywhere in North America; however, as years go on, more states, provinces, and territories are beginning to accept this environmentally friendly practice.

 

Graywater System

gray-water-reclamation

Graywater reclamation systems work with the use of a hand-activated valve. Users can choose when to divert water from the bathroom sink, tub or washing machine to the garden; and when to divert the water to the septic tank or sewage system, preventing overwatering during times of heavy rainfall or sending chemicals to the gardens[xi].

Filter

Within the reclamation system, a basic filter made of mesh is used by which large particles are filtered through[xii].

Surge Tank

The surge tank helps to regulate the flow of water by temporarily storing graywater in order for water not to drain out all at once, causing flooding or backing up into the house. From the surge tank, graywater can go into two places: outside to the irrigation system or through sewer drains[xiii].

There are many different price points for graywater systems. A more advanced system allows treated graywater to become rerouted back into the home or business (toilets, laundry machine, cooling systems)[xiv].

When Graywater Is Not Suitable

There are many advantages of graywater use; however, as you will see below, not all conditions or locations are suitable for this environmentally friendly practice.

In order for graywater to be advantageous for a property owner for outdoor purposes, there must be an abundance of soil, and the soil must not be permeable[xv]. Non-permeable top soil acts as a filter before graywater reaches plants’ roots[xvi]. Contaminants from the water are filtered through a very basic process[xvii]. Envision this: solids from soup being strained out by a colander. Soil performs in a very similar way; contaminants become caught by the grit in the soil, leaving only the nutrients to enter into the roots of the plants[xviii].

A large building such as a mansion may not be an economical choice for graywater use. Due to the amount of plumbing needed to capture graywater in such a large building, and the small number of residents, the cost of the plumbing will outweigh the benefit[xix].

Conclusion

The reality is we unfortunately do not live in a world with bottomless reservoirs. With climate change, population increase and wasted water use, water supply can have a negative impact on the way we live.

For your next project, consider water reclamation and rainwater harvesting systems. By adapting to graywater techniques today, we can be on the forefront of water conservation tomorrow.

 

 



[i]“Greywater Recycling Basics.” LetsgoGreeen.com. Web. 07 June 2013. <http://www.letsgogreen.com/greywater-recycling.html>.

[ii] Tricia Ballad. “Water Recycling at Homes.” Green Living. Web. 07 June 2013. <http://greenliving.nationalgeographic.com/water-recycling-homes-2302.html>.

[iii] Tricia Ballad. “Water Recycling at Homes.” Green Living. Web. 07 June 2013. <http://greenliving.nationalgeographic.com/water-recycling-homes-2302.html>.

[iv] “Recycle Your Greywater Into Your Landscaping”. The Chic Ecologist. <http://www.thechicecologist.com/2010/01/flotender-grey-water-recycling>.

[v] “Rainwater Harvesting and Grey Water Reuse.” Web. 12 June 2013. < http://www.cmhc-schl.gc.ca/odpub/pdf/63132.pdf>.

[vi] “Rainwater Harvesting and Grey Water Reuse.” Web. 12 June 2013. < http://www.cmhc-schl.gc.ca/odpub/pdf/63132.pdf>.

[vii] “Vol. 1 2009 – Rainwater Harvesting Technology”. Greenovation+. Web. 20 June 2013. <http://greenovation.atsspec.net/2009/10/01/vol-1-2009-rainwater-harvesting-technology/>

 

[ix] “Advanced – Educators Stay Green with Rainwater Harvesting.” Web. 24 June 2013. < http://www.braewater.com/learning_center/case_studies/advanced>.

[x] Robert Lamb. “How Gray Water Reclamation Works.” How Stuff Works. Web. 07 June 2013. <http://science.howstuffworks.com/environmental/green-science/gray-water-reclamation4.htm>

[xi] Robert Lamb. “How Gray Water Reclamation Works.” How Stuff Works. Web. 07 June 2013. <http://science.howstuffworks.com/environmental/green-science/gray-water-reclamation4.htm>.

[xii] Robert Lamb. “How Gray Water Reclamation Works.” How Stuff Works. Web. 07 June 2013. <http://science.howstuffworks.com/environmental/green-science/gray-water-reclamation4.htm>.

[xiii] Robert Lamb. “How Gray Water Reclamation Works.” How Stuff Works. Web. 07 June 2013. <http://science.howstuffworks.com/environmental/green-science/gray-water-reclamation4.htm>

[xiv] Robert Lamb. “How Gray Water Reclamation Works.” How Stuff Works. Web. 07 June 2013. <http://science.howstuffworks.com/environmental/green-science/gray-water-reclamation4.htm>.

[xv] “Greywater Recycling Basics.” LetsgoGreeen.com. Web. 07 June 2013. <http://www.letsgogreen.com/greywater-recycling.html>.

[xvi] Tricia Ballad. “Water Recycling at Homes.” Green Living. Web. 07 June 2013. <http://greenliving.nationalgeographic.com/water-recycling-homes-2302.html>.

[xvii]  Robert Lamb. “How Gray Water Reclamation Works.” How Stuff Works. Web. 07 June 2013. <http://science.howstuffworks.com/environmental/green-science/gray-water-reclamation2.htm>.

[xviii] Robert Lamb. “How Gray Water Reclamation Works.” How Stuff Works. Web. 07 June 2013. <http://science.howstuffworks.com/environmental/green-science/gray-water-reclamation2.htm>.

[xix] “Greywater Recycling Basics.” LetsgoGreeen.com. Web. 07 June 2013. <http://www.letsgogreen.com/greywater-recycling.html>.