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Water - This is a question that a city official asked

Hello community,

Can recycled water that has been cleaned be used for a grow? You can use this water for wheat, hay, alfalfa but cannot be used for vegetables. This is the extent of my knowledge. Does anyone have any insight as to the type of water this is & if it can be used for cannabis?Namaste,


Hi Angela!

Are you asking about reclaimed water?

If so, such water can likely be used on outdoor cannabis safely (depending on the status of the water), but I wouldn’t recommend it for indoors or greenhouse cannabis without further treatment. The reason is that reclaimed water typically has all sorts of microbes in it, which would be unsuitable for a controlled environment such as indoors or a greenhouse and could theoretically cause undesired consequences. In an outdoor grow, it is likely such microbes would face competition and be kept in check.

Now, if you have your own method of distillation or purification (IE using water created from AC units), it might become useful for indoors or greenhouse grows with some minor sterilization.

Side note: Reclaimed water can differ greatly in quality, from raw sewage to simple plant runoff.


Thank you so much that’s the perfect reply that I needed. Very helpful


This link may also be of benefit WHO gray water recycling standards


Thank you Ethan.


Depending on the source of the recycled water, you would most likely need to add to your reverse osmosis system (which should be used regardless of the water source, especially for medicinals), a minimum of chlorination and double-UV sterilization and/or ozone injection.


How much water is the deciding factor. If you need a lot of water reverse osmosis is more cost effective. Pain in the tuchas to maintain but really good.

I hate chlorination of water from the people handling side. Just to prone to accidents. Most codes require separate rooms and ventilation. Just saw a news story about a swimming pool gas chlorination, killed to techs. Nasty stuff. It is denser than air, think WW1 and chlorine gas attacks.


Recycled runoff from plants can absolutely be reused, we do it very frequently in large commercial vegetable and flower greenhouse system worldwide (you can save between 40-70% on fertilizer costs, which is huge to a 250 acre greenhouse operation).

The problem with UV and chemical (ozone, hydrogen peroxide, chlorine, etc) treatment is that the oxidizing process destroys chelates, and virtually all iron content in the treated runoff, which means the runoff solution is now missing just those elements and not others, making it hard to inject the right fertilizers at the right concentrations when switching back and forth between mixing runoff with fresh water and using only fresh water. It’s doable, but tricky.

There’s a new system that uses hemo-dialysis filtration technology to actually physically filter out bacteria, fungal spores, and viruses (it filters down to 0.0034 microns, and the smallest dangerous microbes, viruses, only go down to 0.02 microns). Not sure about availability in the US right now, since it’s a newly developed system from Israel, but we can get one here if anyone is interested.

If you’re talking about using grey water (completely different than recycled runoff), then I would say the sterilization system would also need, at the very least, a carbon filter after it to remove any detergents or any other nasty chemical that may get washed down whatever drain this water is collected from. RO would be even better to ensure nothing makes it through.

Hope that helps!


Hi Josh,

HydroLogic has solutions for purifying nutrient runoff water using reverse osmosis technology that are actively being used in in commercial cannabis cultivation facilities throughout North America. For more info on our HyperLogic Nutrient Runoff Filtration System and overall ‘Minimal Liquid Discharge’ plan, you can visit our HyperLogic Commercial/Industrial website here:

We tailor each waste water treatment solution based on the client’s goals, the facility layout, and the municipal waste water regulations the facility owner needs to comply with.

Let me know if you have any questions and I’ll be happy to help!

Sara S.

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