In the following article, Nicholas Clover, systems engineer with EnviroTech Cultivation Solutions, dives into the issue of water waste within the cannabis industry.
Cannabis growers and water waste
As the wave of cannabis legalization moves across the country and more cultivation facilities come online, most regulators have not yet begun to crack down on the significant amounts of water wasted in cannabis production. A typical 40,000 sq. ft. cannabis greenhouse can easily waste upwards of 10,000 gallons of water per day when irrigation runoff water isn't captured and recycled.
Should I recycle the irrigation water in my cultivation facility?
It depends. Eventually, regulators may end up making the choice for you by requiring increased water conservation through some form of recycling. It is important to discuss with your local regulators if any upcoming changes to the water regulations that could affect your decision. The associated financial costs of implementing a closed-loop water system should be considered.
Isn’t it cheaper to recycle water than to waste it?
Most commercial growers aren’t recycling their irrigation water because water is generally cheap in the U.S., with costs averaging just $1.50 for 1,000 gallons. Recirculating systems also require the installation of costly underground tanks and pumps to collect the run-off water from plants, commonly known as leachate. From these underground leachate tanks, additional equipment is required to sterilize the water to prevent pathogens from damaging the health of your crop. Commercial UV and ozone systems can easily run in the $30k-50k range and can have large footprints where valuable floor space remains at a premium. Once the leachate has been treated, it is returned to above-ground storage tanks where it is ready to be used for irrigation again.
Am I putting my plants at risk by using recycled irrigation water?
Plant health and nutrient composition in recirculating systems remain a concern. Cannabis plants consume various nutrients at different rates throughout its lifecycle. When utilizing a closed-loop system, growers will need to perform frequent water sample analysis in order to monitor and compensate for individual nutrient uptake and deficiencies. Samples must then be sent to a lab for processing where costs can add up quickly for these services.
Where do we go from here?
As profit margins in the industry continue to compress, eliminating costly water recycling equipment remains one easy way to reduce capital expenses. Until more regulators begin to enforce water conservation, drain-to-waste irrigation will remain the most popular strategy due to its low cost and superior control of nutrient delivery to the crop.
Nicholas Clover is a licensed professional engineer with a passion for plants and people. Nicholas has been working in the medical cannabis industry for over a decade, specializing in the design and engineering of cultivation facilities. He currently works at Envirotech Cultivation Solutions -- a cultivation systems integrator based in Richmond, California.