Short answer: usually not. Most Kratky growers use ordinary tap water without problems. If you prefer to remove the disinfectant, how you do it depends on whether your utility uses chlorine or chloramine.
Why tap water contains disinfectant
Water utilities add chlorine or chloramine to keep drinking water free of harmful microbes as it travels through pipes. In the United States the EPA limits both to a maximum of 4 mg/L in drinking water, and typical levels are lower (U.S. EPA).
Chlorine or chloramine?
- Chlorine escapes from water into the air. Leaving water in an open container for a day or so removes most of it.
- Chloramine is chlorine combined with ammonia. It is much more stable and does not leave standing water quickly.
Your water utility’s annual water quality report says which one it uses.
How to remove each one
- Standing water works for chlorine only.
- Activated carbon filters reduce chlorine. Catalytic carbon filters are designed to handle chloramine as well.
- Ascorbic acid (vitamin C) neutralizes both chlorine and chloramine. A very small amount treats a large volume.
Does it matter for plants?
At drinking-water levels, disinfectant is rarely the cause of problems in a Kratky container. Strength, pH and water hardness have a much larger effect. If plants struggle, measure EC and pH before blaming chlorine.
Check the rest of your water too
While you are reading the water quality report, note the hardness and sodium figures. Very hard or softened water is more likely to cause trouble than disinfectant.
Related guide: choosing water for Kratky nutrient solution.
Sources
- U.S. Environmental Protection Agency. Chloramines in Drinking Water.
