cannetix Inc
Well-Known Member
Adressing the Claim That Chlorinated Water Harms The Soil Microbiome & Harms Plants
One of the most prevalent of the many unfounded claims made by members of the Cannabis growing community is the claim that Chlorinated water has a detrimental effect on plant health, primarily the soil microbiome. Although this may seem like a logical conclusion to come to based on the antiseptic properties of Chlorine, it may not be entirely accurate due to how the process of chlorination works and how Chlorine works chemically to disinfect water.
The treatment of municipal drinking water supplies with Chlorine most commonly involves the use of Sodium Hypochlorite, and although decreasingly common, Chlorine gas. When these compounds are added to water, they undergo a series of reactions that result in the formation of Hypochlorous acid (HOCl) and/or hypochlorite ions (OCl-). In basic terms, Chlorine disinfectants work because Chlorine is a strong oxidizing agent that oxidizes organic molecules present in the water, including those that constitute micro-organisms. Unlike “Antibiotics” in the conventional sense of the term, which work in much lower concentrations through biochemical pathways (ie. The inhibition of certain enzymes essential to the survival of the organism), oxidizing disinfectants work through much more direct, abiotic means and their efficacy is much more dependant on dose (a concept known as disinfectant demand). Chlorine that is added to municipal water for disinfection purposes is added to the water in what is known as a contact chamber, which is a baffled basin that provides sufficient detention time of chlorine contact with water for disinfection to occur. As organic molecules are oxidized, Free Chlorine is “consumed” and thus does not have a prolonged disinfecting effect. After chlorine demand is met and disinfection occurs, most of the added chlorine is gone with only small residual levels of free-chlorine remaining. Chlorine that is “consumed” has been reduced to its most stable oxidation state (Cl-1) also known as Chloride, which is an essential trace nutrient for growth in higher plants. Chloride deficiency in higher plants causes well-documented effects including wilting, restricted and highly branched root system development, leaf mottling and chlorosis.
The residual free-chlorine present in municipal water supplies is, generally speaking, enough to prevent the growth of micro-organisms in the distribution network (pipes) were the cleanliness of the water and the use of antimicrobial materials such as copper result in a low disinfectant demand. Soil, unlike the sterile or near-sterile municipal water distribution network, however, has a massive amount of organic material and massive, well-established colonies of bacteria and other micro-organisms. This gives soil an extremely high disinfectant demand, one that can simply not be met by residual chlorine levels present in municipal water supplies. In soil, this high disinfectant demand is more accurately referred to as high microbial biomass.
Although water distribution networks are very clean, the presence of trace contaminates does result in the further consumption and depletion of free chlorine, resulting in residual chlorine levels at your faucet that are even lower than those present in the distribution network (note that the use of Chloramines can prolong the disinfecting effects of Chlorine in the distribution network). The developed world has been Chlorinating water for approximately 60 years and to date, there have yet to be any published studies suggesting that residual chlorine present in tap water has any negative effect on the soil microbiome or plant life in general. On the other hand, there are published studies indicating that free-chlorine, due to its oxidizing nature, can increase Assimilable organic carbon (AOC) in water. High AOC concentrations result in biological instability and can increase long-term microbial growth. The chlorination of water does result in the formation of a number of byproducts, mainly Halogenated trihalomethanes (THMs) and haloacetic acids (HAAs). Although these compounds have been associated with human cancers, they also have not been implicated in having any negative effects on the soil microbiome or plant health, nor do they concentrate in plants and thus do not pose a significant risk to humans through bioaccumulation or biomagnification in plants from the agricultural use of chlorinated water.
It's only logical to assume that if Chlorinated water had any detrimental effects on beneficial soil micro-organisms, that it would also have similar detrimental effects on pathogenic micro-organisms responsible for plant diseases such as bud rot, powdery mildew, etc. but any such effects on either end of this spectrum are highly unlikely.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC542550/ Photosynthesis, Growth and the role of Chloride
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC540579/pdf/plntphys00391-0034.pdf Chlorine (Chloride), a Micro-Nutrient for Higher Plants
http://www.alcanada.com/index_htm_files/Chlorine vs Chloride.pdf Chlorine vs Chloride
https://www.ncbi.nlm.nih.gov/books/NBK234590/ The Disinfection of Drinking Water & The Concept of Disinfectant Demand
http://dnr.wi.gov/regulations/labcert/documents/training/cl2chemistry.pdf The Fundamentals of Chlorine Chemistry & Disinfection
http://www.owp.csus.edu/glossary/chlorine-contact-chamber.php Chlorine contact chamber
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4080524/ The effect of chlorine residual on the growth of bacteria in pipes
http://soilquality.org.au/factsheets/microbial-biomass Microbial Biomass of soil
https://www.ncbi.nlm.nih.gov/books/NBK216601/ Biological Quality of Water in the Distribution System & some notes on free-chlorine depletion
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4433738/ Chlorine Content in Tap Water & The Decay of free-chlorine in drinking water at the point of use
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC202520/ Factors promoting survival of bacteria in chlorinated water supplies.
http://www.sciencedirect.com/science/article/pii/S0304389406012878 Chlorination byproducts
https://www.des.nh.gov/organization/commissioner/pip/factsheets/ard/documents/ard-ehp-13.pdf Trihalomethanes: A health information summary
https://www.epa.gov/dwreginfo/chloramines-drinking-water Chloramines and their prolonging effect on chlorines disinfecting properties in the distribution network
