Articles
MAKING THE MOST OUT OF USED WATER
| 24 August 2005
MAKING THE MOST OUT OF USED WATER
If you use an average top-loading washing machine six times a week, it’ll probably send close to 1000 L down the drain in one week alone. Add to that your dishwashing, shower and bath water, and you’re soon up to 4000 L a week for the average family of four.
The wastewater from our kitchens, laundries and bathrooms (not from toilets) is called ‘grey water’, or ‘used water’ — it really isn’t wastewater, as you can still make good use of it in your garden. And if you invest in a properly installed grey water pre-treatment system, you can also use grey water for toilet flushing or in the laundry.
However, there are some environmental and health concerns with grey water, so it’s important you contact the environment protection agency in your state, your health department and local council before you start reusing it.
If you want to reuse manually saved grey water:
Use only the rinse water from your washing machine to water the garden — it contains lower concentrations of detergents.
Water different areas in your garden to avoid chemical build-up in one particular area.
Avoid detergents with sodium perborate — it's a bleaching agent and a source of boron, which may reach toxic levels if it accumulates in one spot.
For hygiene reasons, use grey water only on plants that won’t be eaten.
Don't use dirty nappy water.
Don't reuse your wastewater if anyone in your family is unwell or has a contagious virus.
Don't use water from a dishwasher because the detergents can make it quite caustic.
Choose detergents with low or no phosphorus, especially if you live near a water source.
It’s best not to store grey water and keep adding to it (unless it’s a properly installed system), as bacteria in the water will multiply quickly for the first few days, especially if it’s warm. They’ll then stabilise and start to die off, unless you add more grey water.
If you want to install a grey water pre-treatment system, do all of the above, plus:
Consult your sewage removal authority if you intend to redirect all or a major part of your used water.
Consult a licensed plumber for advice on the best system for your needs.
Inform your water supply authority of any changes to your plumbing.
