A leading scientist in biowaste research is urging other regions to follow a Northland nursery that's using recycled water from a wastewater treatment plant, especially during dry spells.
Dr Maria Gutierrez-Gines from the Institute of Environmental Science and Research (ESR) described as "fascinating" the use of recycled water by Whangārei-based Alter-Natives Nursery and Landscaping for several years.
The recycled water is drawn from the nearby wastewater treatment plan run by the Whangārei District Council. It's believed to be the only commercial nursery in the country to use treated wastewater.
Up to 150,000 litres a day is used in the thick of summer but that volume decreases during winter when it rains.
Wastewater at the Whangārei Wastewater Treatment Plant is sterilised and treated before it's pumped into a wetland on Kioreroa Rd, across the road from the nursery, and then out to sea.
The nursery pumps it into two tanks before the water goes from the treatment plant to the wetland.
Gutierrez-Gines said she has not heard of any other nurseries throughout New Zealand that use recycled water from wastewater plants.
Alter-Natives has 500,000 plants spread over four hectares during its peak in spring and autumn.
Director Phil Grindle said the recycled water came to the nursery equivalent to used bath water and his employees filter, chlorinate, and UV sterilised it before use.
"Cost is a major benefit and then there's sustainability benefits. Nutrient wise, it's just like normal water. The team at the wastewater plant has pretty serious sensory equipment to detect E. coli or particles."
His nursery has a resource consent to use recycled water which the business buys at a cheaper price than reticulated water.
The consent does not specify the maximum amount of recycled water that can be drawn.
Gutierrez-Gines said recycled wastewater has a lot of nitrogen and phosphorus which meant users could avoid using fertiliser.
"We've been working for over 10 years trying to find sustainable solution for biowaste and wastewater in New Zealand and I find it very fascinating that the nursery is growing natural plants from wastewater.
"Not all plants grow the same so it's more about the economic benefits and with all the problem of water shortage, why not use recycled water which will ultimately be disposed of into the sea?
"I think it's a good idea for other places to use recycled wastewater as long as potential risks are taken into account because we'll continue to have water shortages," she said.
Gutierrez-Gines said ESR, in collaboration between New Zealand's Crown Research Institutes, universities and research partners, have been doing a lot of research from toxicology and microbiology to understand the risk of pathogens and worked closely with local councils.
She said the Whangārei District Council informed them about Alter-Natives' use of recycled water and researchers decided to look deeper into it when funding was made available.
"This is the first time that we thought about working with nurseries, so I am not aware of this happening in other parts of the world, but I suppose it must be common," she said.