Project Round
Project Number
Research Organisation
Alternative Technology Association

Testing Household Greywater Treatment Systems

The Challenge

On average, Victorian households use 240,000 litres of water a year.

The Alternative Technology Association (ATA) estimates that as much as 40 per cent of household mains-water could be saved by recycling “greywater”. Greywater is generated by showers, laundries and sometimes kitchens and can be reused for watering lawns, gardens and flushing toilets.

As well as representing significant water savings, the nutrients in greywater are beneficial for plants, enabling them to survive periods of low rainfall. However, inappropriate volumes, chemicals, salts and soaps can damage plant life and possibly contaminate groundwater. Additional risks include soil degradation and the transmission of disease.

In order to improve take up of greywater recycling, the ATA set out to develop a better understanding of current greywater usage.

The Project

With the assistance of a Smart Water Fund grant, the Alternative Technology Association (ATA) developed a three-tiered approach to assess the viability of greywater systems. This included:

  • On-Site trials to monitor the installation, operation and maintenance of commercially-available greywater systems such as:
    1. Diversions to gardens via trenches
    2. Diversions to gardens via drip-fed irrigation
    3. Diversions to toilet cisterns
    4. Above-ground greywater treatment systems
    5. In-ground greywater treatment systems
  • A market survey to evaluate greywater reuse throughout Australia
  • A communication campaign to raise awareness about greywater reuse and inform the public about the project’s progress and outcomes

The Outcome

Lessons Learnt

On-Site Trials: The ATA evaluated the usability and effectiveness of six households’ greywater systems in the Melbourne metropolitan area. Sites were selected to reflect a diverse range of households, water consumption patterns, soil types, garden sizes and water authority areas.

The ATA found that despite the variety of households participating in the study, greywater systems reduced water consumption in all but one household by as much as 33 per cent.

“Twelve months ago our peak water usage was over 1,200 litres per day. Now, our daily use in the summer is approximately 600 litres, and we hope to reduce this further,” says Marion Eyers, a participant in the trials.

The study also found greywater diversion is a cost-effective way to reduce total water  consumption.

Test households were more aware of the need to conserve water and paid attention to what went down their drains as a result of utilising the systems.

Market Survey: The ATA surveyed 120 members nation-wide about their greywater reuse. Results indicate that the majority of respondents (88%) were motivated to adopt greywater systems in an effort to conserve water.

However, permanent greywater systems are often installed without council consultation or  expert assistance, and without an understanding of the associated risks. More than one in four respondents irrigated vegetables with untreated greywater; an unsafe practice that can lead to soil contamination and illness.

Education was identified as a key to reducing dangerous greywater usage and ensuring  householders understand how to properly use and care for greywater systems.

Communication Campaign: Throughout the project, the ATA engaged in a number of communication activities to educate the public about safe and effective use of greywater systems.

Progress reports and final outcomes were published in the orgranisation’s internal newsletter, as well as in local and state newspapers and magazines.

The ATA also participated in seven public forums which addressed: Greywater Do’s and Don’ts as well as Why and How to Use Greywater. Their conference, “Beyond the Grey”, brought together over 150 people from local government, industry and the general public.

The Benefits

The ATA’s Smart Water Fund project has provided valuable insight into the current use of greywater systems and their potential to reduce the amount of potable water Victorian households consume.

“Our project has important learnings for homeowners and the community. We can now provide the community with detailed information about grewater systems, allowing a more informed decision to be made that best supports their efforts to conserve water,” said Robin Merrick, ATA Project Leader.

The ATA is participating in the Victorian Government’s Regulatory Review of Alternative Urban Water Supplies and will bring the outcomes of the greywater project to this decision-making forum.

Supporting documents