Greywater

Whether its bathwater, shower water, laundry water or the water you washed your veges in, it’s useful for the garden. Collecting household grey water needn’t be complicated. Use a bucket to scoop the water out after a bath or have a wide bucket handy to catch water while showering.

Waste water that isn’t recommended for garden use is toilet water (called ‘black water’) and the ‘dark grey’ dirty dishwater from the kitchen sink or dishwasher that is high in chemicals and organic matter. Water containing food particles encourages bacteria to grow faster meaning more potential for pathogens. However, a lot depends on how big your garden is. While a little spread over a large area may be harmless, fats and grease decompose slowly in soil, so too much can be a problem.

Bacteria and other microorganisms are everywhere, including in the garden soil and on plants. A few of them are germs which cause illness. This is why grey water is not recommended for use on edible plants. It’s good to know, however, that plants don’t get sick from human bugs and that bugs in greywater will not migrate into fruit. It’s important not to store grey water for more than a day, or bacteria will start to multiply.

There is some concern that washing machine water contains microfibres from synthetic clothes that may be harmful for the environment, although the extent of this is still unknown.

For plants, the most harmful chemicals in greywater are sodium (salt), boron and bleach. These occur at various concentrations in soaps, detergents and washing powders, including those labeled ‘biodegradable’.

Another concern is pH, with greywater inclined to be more alkaline. How much this effects plants depends on the pH of the soil as well as the pH of the greywater. In rainy weather the risk is less. Yates Greywater Fertiliser helps neutralise the alkaline effect of soaps and detergents and contains a bactericide to kill unwanted bugs. Turn to page 38 to be in to win this new product.