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Reuse Greywater For Water Conservation

Water scarcity is becoming a worldwide issue rather than a remote concern. This is exacerbated by continuous strain on the limited supply of water due to urbanisation, population growth, and the increasing effects of climate change.

According to the International Water Management Institution, urban water consumption is forecasted to increase from 1995 to 2025 by 62%. With additional increase in population and climate change, water shortage is likely to manifest in 2050. For these reasons, it has become imperative that we find adaptable solutions in which we can maintain the existing water resource whilst seeking methods in which we can reduce the demand of potable or drinking water.

Greywater reuse is receiving more traction as a solution to urban water management as it offers a straightforward onsite but effective option to shift our water-use patterns. Water reuse is significant because it may simultaneously address two urgent issues: environmental sustainability and water scarcity.

What is Greywater?

Greywater is wastewater that can be reused for other purposes. It makes for as much as 70% of all residential buildings water use. Although greywater and blackwater are typically combined, separating the two, greywater on its own provides several reuse opportunities such as toilet flushing, and garden irrigation. This can additionally assist in lowering potable or drinking water use in arid areas by up to 30% for households. Furthermore, saving money on garden irrigation through reuse can boost household savings by 40%.

Greywater can be collected from the source by installing a plumbing system from an outlet of a bathroom/kitchen to a garden or for toilet flushing. To this, a greywater treatment system such as wetlands, green walls can be installed to help filter large particles, nutrients and pump treated water through irrigation pipes.

Blackwater on the other hand, is toilet water that contains faecal matter and urine. Faecal matter is a breeding ground for harmful bacteria and pathogens that can cause diseases.

Advantages of using Greywater in your garden

Water Conservation: The use of greywater provides us with an opportunity to use an average of approximately 35 – 234 litres (per person per day, depending on lifestyles) of greywater which can be repurposed for garden irrigation or toilet flushing where little human contact is achieved.

Cost-Effective: The use of greywater is inexpensive and for this reason, the water bills can be drastically reduced while investing in a greener future.

Lush Landscapes: Watch your garden flourish! Greywater provides essential nutrients such as total nitrogen (2.75 to 21.00 mg/L) and total phosphorus (0.062 to 57.00 mg/L) that mainly originate from the kitchen (kitchen residues/waste) and hand basins (soap), respectively. These nutrients nourish our soil and plants, promoting healthier growth and vibrant blooms.

Resilience to Drought: Water-efficient measures (greywater reuse) make your garden more resilient to water scarcity and drought conditions, ensuring continued operations during challenging times.

Safe and Sustainable use of Greywater

  • Greywater has been shown to be a potential hazard to human health. Its handling must be done with care to reduce the risk of infection. Use gloves when handling greywater.
  • Greywater containing potentially infectious pathogens should not be used for overhead irrigation. This includes water used to wash nappies or soiled sheets.
  • To reduce odour and bacteria, greywater should be used within 24 hours of collection. 
  • Subsurface irrigation is the best way of watering since it protects against possible microbiological health hazards.
  • To avoid waterlogging and prevent root damage, it’s critical to disperse greywater uniformly in your landscape (and not just in one spot).
  • When irrigating with greywater, it is not advisable to use spray irrigation. This is primarily due to the increased risk of exposing people to greywater.
  • Where possible, greywater should not be used for an extended period in the same area. This may result in the accumulation of different components found in greywater that may negatively impact the plant’s health.

Water Wise has developed a simple and cost-effective solution to treat domestic greywater for use in the landscape/garden. This low-cost sub-surface horizontal constructed wetland system is designed to be implemented in garden and urban landscapes and can be adapted to suit the volume of greywater produced. The design of this system ensures that there is no pooling of greywater on the surface and no smell or water-borne pests such as mosquitoes.

The Water Wise Guide to DIY Constructed Wetlands can be accessed and downloaded for free by going to the Rand Water website, clicking on the Water Wise logo and looking under the Green Industry tab or follow this link.

#BeWaterWise

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