Water Treatment Letting Stand on calathea
What's Happening
Municipal water treatment facilities add chlorine or chloramine at 0.2-4.0 mg/L to disinfect water supplies. Chlorine is volatile and evaporates when exposed to air, but chloramine (used in 30%+ of US municipalities) is stable and does not dissipate through standing. Chlorine gas dissolves in water forming hypochlorous acid which oxidizes root tissues and disrupts beneficial soil microbiology. Letting water stand allows 80-90% of free chlorine to off-gas within 24 hours.
How to Fix It
- 1
Fill watering can or open container with tap water
- 2
Leave uncovered at room temperature for 24-48 hours minimum
- 3
Place in location with air circulation to accelerate chlorine evaporation
- 4
Use within 72 hours to prevent stagnation and bacterial growth
- 5
NOTE: This method removes chlorine only - fluoride and minerals remain
How to Prevent It
Use standing method as minimum baseline for all houseplants. Combine with monthly soil flushing using distilled water to address mineral accumulation that standing cannot remove.