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What is greywater?

We all know how much Australia struggles during a long dry summer where rainfall is rare and water supplies can fall.

In Melbourne our main dam, the Thomson Reservoir, reached a record low of just 16 per cent capacity in 2009. The Thomson Reservoir is located approximately 123km east of Victoria, just past Mount Baw Baw.

Heavy rainfall through 2010 and 2011 helped Melbourne’s 10 dams reach an average current (and much more comfortable) 80 per cent full. The three largest damns are on average 60 per cent full, while the smallest, O’Shannassy Reservoir (located 13km northeast of Warburton) is 84 per cent full. (Dam level statistics have been sourced from here.)

What is greywater

What is greywater?

We refer to any domestic wastewater from most non-toilet plumbing systems throughout the home. That includes sinks, showers, and laundry appliances. Greywater is different to sewerage, also known as black water. Compared to sewerage, greywater is relatively clean, but it still requires treatment in order to make it reusable.

The word “wastewater” has poor connotations when it comes to water recycling and usability, and it conveys the notion of water that is unusable and therefore ‘waste’. A term that better captures the truer nature of greywater is ‘used’ water.

Common contaminants found in greywater include:

  • Salt
  • Food particles
  • Detergents
  • Soaps
  • Chemicals
  • Bacteria


How is greywater recycled and treated?

Greywater must be treated in a way that does not compromise both people’s health and the environment.

Greywater is easier to treat than sewerage (black water) thanks to generally lower levels of containments. In separate grey and black water systems, grey water can be treated within your own home, and used almost immediately.

Generally three stages are followed during treatment of greywater:

  1. Solids – solids like lint, hair, and food solids are filtered out of the water
  2. Chemicals – chemicals are removed through chemical treatment or micro-organisms (micro-organisms can convert chemicals into by-products like carbon dioxide – cool, huh?)
  3. Disinfection – this step is not crucial but sometimes chorine or UV light is used to disinfect greywater (Source)


Where can greywater be used?

Once it has been properly treated, grey water can be used both commercially and domestically for a number of purposes. It can be used for almost any household task less consumption. For example, greywater can be used:

  • In the laundry as part of your washing machine cycle
  • In the bathroom for toilet flushing
  • In the garden for your plants


Better yet, using grey water in instances where it can replace fresh water could mean lower water bills and less demand on your local water supply. Additionally, a greywater filtration system reduces the strain on your septic system. Overtime, this can reduce maintenance and extend your septic system’s overall lifespan.

Depending on your local council, grey water may be used in the garden and on lawns without any prior treatment.

Greywater cannot be used as drinking (potable) water.


How do we waste water?

Greywater is a great way to reduce the strain on our precious resources by reusing water that is deemed perfectly usable (except as drinking water).

In a year, an average household wastes water due to the following:

  • Running a dishwasher or washing machine cycle when it’s not full
  • Letting the water run while you’re brushing your teeth, washing dishes, or shaving
  • Ignoring leaks
  • Long showers

Grey water

Interested in a greywater system? Call our plumbers in Melbourne

CHOICE.com.au has a great guide that will help introduce you to greywater treatment systems for your home.

If you require any more information or advice, or would like to arrange an inspection to see how a greywater system could be implemented in your home, contact Watermaster Plumbing today. We’re a team of qualified plumbers in Melbourne ready to help you make more efficient and safer water-saving solutions in your home. Call us now or fill in this form.

A greywater system will help your household save water and make better use of reused water: it really is more black and white than you’d think!

2022-01-25T05:27:12+00:00 February 8th, 2017|Blog|