Large-scale cannabis cultivation requires many resources. Water is one of the most important ones, and also the most precious. As more cultivation operations are created throughout the US, the demand for water increases. At the same time, water is limited, and it goes without saying that high water consumption is not sustainable. That is why New Frontier Data, in collaboration with the Resource Innovation Institute, have released a report titled “Cannabis H2O: Water Use and Sustainability in Cultivation” that explores the ways in which water is used by legal cannabis growers, establishing benchmarks for water use across different types of facilities. The report also highlights the innovations that foster water efficiency, offering advise to advance water-use efficiency.
Depending on the cultivation setting, the amount of water used varies. Indoor facilities use the most water per year, also because they carry out more cycles compared to outdoor cultivations, for instance. “On average, facilities use 121 gallons per square foot per year, with indoor facilities averaging 209 gallons, compared to outdoor facilities averaging 11 gallons per square foot per year,” the report says.
Additionally, the irrigation practices carried out in said facilities influence water consumption. Generally speaking, using precision irrigation instead of hand-watering plants already cuts the water use, according to the report. Another factor that matters is the type of substrate used for growing cannabis: rockwool, for instance, has a better water holding capacity than soil, which consequentially reduces the water consumption. At the same time, when it comes to rockwool, the question of sustainability remains with regards to disposing the plugs once the cycle is over.
According to the report, an effective way to save water is to reuse the condensate collected in HVAC systems, especially now that water-recycling solutions are getting more common, even though some are still concerned about the spreading of pathogens or heavy metals.
With the effects of climate change becoming more evident, the report calls for regulators and governments to incentivize growers to increase their water efficiency.