RAIR in Michigan is a 30,000 ft2 licensed producer that recycles all of the water used in their facility. Watch the complete episode about Air & Water Treatment here.
They do this for environmental reasons and to wildly improve their operational performance. Eliminating water use directly lowers their cost of production. Water bills have been reduced to less than $200/month for 22,000 ft2 of canopy.
They begin by purifying a small replacement amount of input municipal water through reverse osmosis and then combining it with fully cleansed water recovered from unused nutrient fertigation liquid. This surplus nutrient liquid is flushed from their dosing reservoirs when on a weekly basis to maintain their nutrient recipes to a precise level.
Finally, and most important, RAIR recaptures humidity that is aspirated into the rooms when plants process light energy into carbohydrates for growth through photosynthesis. Moisture from the Heating, Ventilation, and Air Conditioning (HVAC) system is recaptured and fed back into their water cycle. The HVAC reclaimed water is essentially distilled but typically has some level of microbial life that has to be cleaned to reach reuse purity. This is done using an ozone generator, an embedded ultra violet (UV) light, 2 carbon filters, 2 DI filters, and a calcite filter.