can i run the washing machine water onto the lawn

Greywater is wastewater from showers, baths, basins and the laundry, but not from toilets and generally not from the kitchen, because kitchen water carries fats and food solids. The regulatory line is between simply diverting it and treating it.

Diversion

• Generally permitted for subsurface or covered irrigation, not for spraying, and not for anything that pools on the surface.
• Must not be stored, usually beyond a very short period, because untreated greywater turns septic quickly.
• Must not be applied to root vegetables or anything eaten raw.
• Needs a diverter valve so the system can go back to sewer, which is essential in wet weather and when using bleach.
• Installation involves the sanitary drainage, so it is licensed plumbing work.145

Treatment systems

A greywater treatment system produces water clean enough for wider use, including toilet flushing and surface irrigation in some approvals. These require council approval, use an approved system model, and carry ongoing servicing obligations similar to an aerated septic system.

Practical points

• Choose laundry products low in salt, phosphorus and boron. Ordinary detergents will damage soil structure and plants over time.
• Rotate the application area rather than sending everything to one spot.
• Stop diverting when using bleach or when someone in the house is unwell.