Greywater Recycling

Any household wastewater with the exception of wastewater from toilets (aka blackwater) is know as Greywater.  Typically, 50-58% of household wastewater is greywater from kitchen sinks, dishwashers, bathroom sinks, tubs and showers.  If you use a composting toilet, 100% of your household wastewater is greywater.

We highly recommend Greywater recyling for irrigation because of the following benefits:

• Reduce fresh water use – when the weather warms up, almost half of the water consumed by the average household is for outdoor use.  If we capture the indoor greywater for use outdoors, we can cut water usage in half.
• Reduce strain on septic system or treatment plant – Greywater makes up the majority of the household wastewater stream, so diverting it from the septic system extends the life and capacity of the system.  For municipal systems, decreased input means more effective treatment coupled with cost savings.
• Develop otherwise unsuitable real estate – a Greywater recyling system, along with the use of composting toilets, can enable the development of property that is unsuitable for a septic system.
• Groundwater recharge – Greywater recycling for irrigation replenishes groundwater, helping the natural hydrologic cycle to keep functioning.
• Plant growth – Greywater can support plant growth in areas that might otherwise not have enough water.
• Maintain soil fertility – the nutrients in the greywater are broken down by bacteria in the soil and made available to plants.  This helps to maintain soil fertility.
• Enhance water quality – The quality of groundwater can surface waters are much better preserved by the natural purification processes the greywater undergoes in the the top layers of the soil than by any engineered water treatment.

Before you get too excited, there are a few drawbacks to consider:

• If you soil is either too permeable or not permeable enough, you may not be able to recycle your greywater, or you may need a system with some modifications.
• You need enough soil to process the greywater and enough plants to use it.
• If it’s too wet to benefit from irrigating with greywater, there may be a better way to dispose of it.  If it’s too cold, you will only be able to recycle in the warmer months.  In colder climates, the heat in the greywater may be more valuable than the water itself.
• Many jurisdictions do not have clear guidelines regarding greywater processing.  With water shortages looming in the near future for many regions, this may change sooner than later.  Health concerns are often cited as the reason for not allowing greywater recycling, although there has never been a documented case of somebody becoming sick as a result of exposure.
• Where legal requirements dictate a complex system and there is only a small flow of water, greywater recycling is not economically feasible.
• If the Greywater system you are considering is more expensive and requires more maintenance than a properly functioning septic or sewer system.

For more information, please visit Letsgogreen.com

The City of Vancouver has designed and manufactured rain barrels (pictured below) for use by residents for garden irrigation. The City subsidizes the cost by 50% and has sold over 2000 to date and counting.  For more information visit vancouver.ca.