The one of cannabis is a multi-million dollar industry in the state of California, yet only 12 counties are legally allowed to grow it outdoors. That's maybe why cannabis is largely cultivated indoors in spaces equipped with industrial high-powered lighting systems that leave a large carbon footprint behind. Plus the few open-air setups in the state have to face substantial regulatory costs and heavy taxation.
But the ever-growing love for this kind of grows is also likely to bring about many serious environmental issues. A research work published in the Journal of Energy Policy claiming the cannabis industry to use 1 % of the U.S's energy supply served to confirm what another study released the year before had already stated: cannabis cultivations eat $6 billion every year in energy, more or less like the energy needed to supply 1.7 million homes.
Water, another major issue
Water is never in abundance indoors either, especially in California, where droughts are rather common and the risk of groundwater contamination from the use of nitrate-rich fertilizers in large-scale crops is fairly high.
And, like any other plant on earth, cannabis needs water to live. Water is the plant's main source of nutrients. Without it, cannabis wouldn't be able to survive. However, for plants to become strong and healthy, considerable attention should be paid to the type of water you're providing them with for it can contain a series of pollutants.
Pollutants that can prove either safe or harmful to the health of your cannabis plants. Each grower must know where to get clean water and how to treat contaminated water so it can be used in their cultivation.
How and where to get water for your indoor grow
1- Rainwater collection systems
One of the most sustainable ways to get water is to create a rainwater tank or grey water system with water from baths, sinks, showers, and washing machines. Both methods work great under the right circumstances and are incredibly cost-effective as well as environmentally-friendly.
- Advantages: Long service life. Low maintenance. They're particularly suitable for regions with some periods of drought when water is in short supply. Using a grey water system is an excellent way to recycle domestic wastewater.
- Disadvantages: Unfortunately, in many jurisdictions, rainwater collection and grey water reutilization are very much limited. Building a simple water collection system could prove rather affordable; the necessary seed capital is still a major challenge, though. All the water you get to collect, be it rainwater or grey water, must be adequately filtered and stored.
2- Non-filtered tap water
Contrary to popular belief, non-filtered tap water is not a death sentence for your plants because water quality varies greatly according to the water treatment protocols in each county. Some cities use hard water with high levels of contaminants such as chlorine, calcium, and magnesium. Water that is low in these chemicals may not kill the plant but it will definitely have a negative impact on the biological activity of the substrate.
- Advantages: Tap water is cheap and readily available, meaning you could use as much as your plants require you to. Besides, virtually no extra work is needed once the pH levels and the pollutants have been tested and adjusted. In order to get rid of chlorine, for example, all you have to do is let it stand for 24-48h and it will evaporate all by itself.
- Disadvantages: This may not be a viable option for growers living in cities with highly treated water supply. Organic farmers will definitely notice how badly the chemicals in treated water can affect the biological life of their substrates.
3- Bottled water
It's a relatively cheap way to get clean unpolluted water for small-scale indoor grows. Most stores have bottled distilled water on sale and many companies distribute it at reasonable prices.
- Advantages: Water is not so pricey as long as it's in small amounts. Easy to obtain. It's safe for the plants and needs no additional filtration.
- Disadvantages: Bottled water supply expenses will build up over time. Suitable for small producers. Too expensive for large-scale growers. Plus it has a heavy impact on the environment, mostly as far as the bottle-making process and transportation costs go.
4- Water filtration systems
An all-time pick for massive scale growers. The market is full of them, yet the most popular of all seem to be the reverse osmosis water filters (RO), which force water through a semi-permeable membrane, leaving all the contaminants behind. RO systems are available at many different prices. A small RO filtration system installed at the kitchen sink will, however, be enough for a small-scale grower. A standard model is capable of filtering up to 189 L of tap water every day, leaving 0 impurities and a pH of 7.
- Advantages: These systems ensure proper filtration and de-pollution, which makes them the safest method to clean massive amounts of water. After the initial investment, it will produce an infinite amount of clean water for your grow.
- Disadvantages: The initial cost of equipment, installation and activation. Even a basic RO system could cost hundreds of dollars, so just imagine what we can get to with more advanced systems! With such a high price, it's impossible for small growers to even dream of laying their hands on a reverse osmosis system.
5- Condensing systems
The vast majority of indoor growers use temperature-controlled spaces to ensure the best conditions for their plants. For this to work out, they rely heavily on air-conditioning systems that end up producing steam and water. While this build-up is usually regarded as waste, many growers have started to use condensing systems as a way to recycle water.
- Advantages: Farmers can collect the water generated by their air-conditioning system using a dehumidifier or directly from its condensation pipe. Besides eco-friendly, the recirculation of water can provide data on the health of your plants (pH levels or nutrient content).
- Disadvantages: There's a major problem with this method and it's that the water you collect will most certainly be full of harmful microorganisms due to the humidity and temperature conditions it's been subject to.