Water regulations continue to shape how CEA operations function, often dictating availability and quality. "Water quality means quantity," Tim Reusch, Sales Manager at Dramm Corporation says, emphasizing the need to understand how water characteristics influence nutrient uptake and overall plant health. Gus Brennan, Head Grower at Greenswell Growers echoes this, sharing firsthand experience in dealing with root disease challenges at Greenswell Growers.
Rachael Warner, drawing from her work at Lufa Farms, highlights that water quality concerns are not uniform. "Every system is unique," she explains. "It's definitely not black and white, and scale is an important factor to consider." With Lufa Farms managing five rooftop greenhouses and one indoor farm in Montreal, they have had to navigate waterborne pathogens such as Phytophthora in their NFT systems.
Water management is at the core of sustainable and efficient CEA, yet it remains one of the most complex and evolving challenges for growers. At the recent Indoor AgCon in Las Vegas, these industry experts shared their insights on the intersection of water quality, plant health, and operational sustainability. Rob Eddy from the Resource Innovation Institute hosted the discussion.
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Adapting to waterborne pathogens
One of the major themes discussed was the growing challenge of waterborne diseases. "Pathogens are evolving as environmental conditions shift," Tim notes, adding that seasonality, temperature fluctuations, and well-water depletion can introduce higher concentrations of iron, sulfur, and bacteria. "Annual water testing is critical. A simple $40 test can reveal significant changes in microbial activity."
Gus highlights the importance of sharing experiences within the industry. "Growers are opening up about these problems, which is great. The only way forward is to learn together. We push our crops so hard that even the smallest mistake can have a big impact."
Rachael points out that rising water temperatures contribute to pathogen proliferation. "In the summer, we see an increase in waterborne diseases. City water quality is also dependent on storage conditions. These variables make managing water quality even more complex."
Managing biofilm and water sanitation
Biofilms, a hidden yet formidable issue in water management, were also a focal point of discussion. "Biofilms in PVC pipes can develop fast and harbour pathogens," Tim explains. "A simple test—cutting open a piece of pipe—can reveal how much buildup is occurring." He stresses the importance of regular disinfection, noting, "Biofilms reduce the effectiveness of disinfectants, ultimately costing growers money."
Warner proposed the need for better biofilm monitoring tools. "We could use BO (biological oxygen) sensors to measure biofilm activity. By incubating water samples in darkness for five days, we can track changes in oxygen demand and get a clearer picture of microbial load."
Tim further emphasized understanding CT (concentration and contact time) values for different pathogens. "For example, E. coli and other contaminants have well-documented threshold values. Knowing these numbers is key to achieving the necessary log reduction."
When asked whether biofilms could harbour beneficial microbes, Gus was cautious. "The risk is too high. Clean is best. Anaerobic bacteria are the real problem, so we should avoid creating conditions where they thrive."
Strategic water treatment for future facilities
If growers are designing a new facility from scratch, what should be their water management priorities? Tim recommends integrating multiple disinfection strategies. "A combination of ozone, UV, activated hydrogen peroxide, or chlorine can be highly effective," he suggests. "UV works best when paired with another strategy."
Gus advises against a do-it-yourself approach when it comes to water quality. "Water management is too critical to leave to chance. Consult experts. In our NFT system, we deal with a lot of moss buildup, so physical filtration is essential."
Rachael stresses the importance of understanding organic material content. "Phytophthora and Pythium are among the top waterborne pathogens. Filtering out organic debris is crucial in preventing their spread."
Investing in clean water from the start
Panelists agreed that a proactive approach to water quality yields the best results. "Clean water is the foundation of a healthy system," Gus says. "We don't recirculate our irrigation water, and we keep fertilizer inputs minimal. The goal is to use as little water as possible while maintaining crop health."
Tim recommends starting with a solid economic assessment. "Begin simple—effective filtration is often the best first step. Identify the pressure points in your system and allocate resources accordingly. Starting clean and staying clean is the best long-term strategy."
Rachael points out that media can also introduce pathogens. "A bad batch of growing media can bring in contaminants. A good protocol is to incubate a media sample, add water, and observe microbial growth after 48 hours."
Gus emphasizes the role of food safety regulations in guiding testing protocols. "We follow strict food safety guidelines because they help us standardize our approach to water quality and pathogen management."
Being holistic in water management
It's about more than just filtration and treatment. "Sanitation practices matter too," Tim adds. "Basic measures like hairnets and clean working environments can make a difference."
"Moving toward a drain-to-waste system is a good step. But before implementing any changes, you need to know your baseline water quality," Gus shares. "Starting with carbon filtration or even reverse osmosis can help set a strong foundation. From there, you can fine-tune fertilizer application based on crop requirements."