Greywater recycling is when wastewater from non-toilet systems such as sinks showers/baths and washing machines is recycled and used for watering your garden.

GDD, (Greywater Diversion Device) directs greywater from a waste pipe from a non-toilet system, (examples given above) into the garden, for use in sub-surface irrigation.

I can include this in project utopia by Putting a greywater system in houses and any other place that uses a reasonable amount of water.