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In an era of increasing water scarcity and environmental concerns, implementing sustainable water management practices has become crucial. Grey water systems offer an effective solution for conserving water resources by recycling household wastewater. By reusing water from showers, baths, hand basins, laundry tubs, washing machines, and dishwashers, grey water systems not only reduce water consumption but also provide cost savings. This article explores the concept of grey water systems, their benefits, and considerations for implementation.


Understanding Grey Water Systems

Grey water refers to the waste water generated from various household activities, excluding toilet flushing and kitchen wastewater. It typically includes water from showers, baths, spas, hand basins, laundry tubs, washing machines, and dishwashers. Figures suggest that a single Australian household can produce around 400 litres of grey water per day, accounting for approximately 40% of total water use.

Grey water can be recycled and repurposed for watering gardens, leading to significant water savings. There are two primary types of grey water systems: untreated direct diversion and domestic grey water treatment systems.


Untreated Grey Water Systems

Untreated grey water systems involve collecting grey water in a storage tank, followed by pumping it into a deep sand filtration bed. This filtration bed comprises layers of gravel and sand, allowing the grey water to percolate through and undergo treatment. Although this treatment process is not chemically-based, the water is still considered “untreated.”

After passing through the filtration bed, the treated grey water is stored in a holding tank. Subsequently, it can be distributed throughout the garden using simple subsurface leaching irrigation systems. Subsurface irrigation is recommended as it minimises direct contact with grey water, reducing the potential transmission of pathogens. Additionally, this irrigation method ensures that water reaches the roots of plants, optimising their hydration.


Treated Grey Water Systems

Alternatively, grey water can be recycled using treatment systems that enhance water quality. These treated grey water systems can upgrade the water to “Class A” quality, enabling its use not only for garden irrigation but also for purposes such as car washing, toilet flushing, and laundry. However, treated grey water systems are more expensive than untreated systems and require more complex installation, often necessitating government approval.

Important Considerations for Grey Water Systems


Before implementing a grey water recycling system, it is essential to consider the following factors:

  1. Adhere to Government Guidelines: Always consult and adhere to the local council, state, county, shire, and other government requirements, regulations, and guidelines pertaining to the use of grey water.
  2. Professional Installation: Engage a licensed plumber for the installation of your grey water system to ensure compliance with safety standards and optimal functionality.
  3. Subsurface Irrigation: Only use untreated grey water with watering systems that operate below the soil surface. This reduces direct contact with grey water and minimises the risk of pathogen transmission.
  4. Grey Water Sources: Divert untreated grey water specifically from sources such as baths, showers, and laundry rinse cycles. This ensures that water containing potentially harmful substances from toilets and kitchens is not reused.
  5. Treated Grey Water Benefits: Treated grey water has undergone additional filtration processes to remove nutrients like nitrogen and phosphorus, making it safer for larger-scale use. Consider using treated grey water for applications where higher water quality is required.
  6. Fertilizer Usage: When using untreated grey water in your garden, you may need to reduce the amount of fertilizer applied since grey water already contains certain nutrients. Seek advice from local nurseries to ensure proper plant health.
  7. Vegetable Gardens: If you consume vegetables raw or slightly cooked, it is advisable to avoid using grey water for irrigation to minimise the risk of potential contamination. Exercise caution when considering the use of grey water on vegetable gardens.
  8. Monitoring Plant Reactions: Observe how your plants respond to grey water irrigation and consult local nurseries or gardening experts if you notice any adverse effects or changes in plant health
  9. Complementary Water-Saving Strategies: Grey water recycling should be integrated into a comprehensive water-saving strategy that includes reducing overall water consumption and rainwater harvesting for various household purposes.



Grey water systems offer an effective means of conserving water and reducing reliance on freshwater resources. By recycling household wastewater, these systems contribute to significant water savings, leading to lower bills and a more sustainable lifestyle. Whether through untreated direct diversion or treated grey water systems, homeowners can make a positive impact on the environment by implementing grey water recycling as part of a broader water-saving strategy. Embracing sustainable water management practices is crucial in addressing water scarcity and promoting a greener future.