Expert: Sarracenia Northwest - 4/28/2011

Question
Will leaving a gallon of tap water out for two days be sufficient in getting out minerals? Or does that only work for getting rid of chlorine?

Answer
Leaving the water sitting has no affect on mineral levels.  Minerals never evaporate out of water.  Instead, leaving the water to sit actually increases mineral concentration because you're reducing the volume of water through evaporation.  This is opposite of what you want.

Letting the water sit to release chlorine only works if the water is chlorinated with chlorine gas.  If your water supply uses chlorine additives similar to bleach, then letting the water sit won't have any affect on chlorine content.  Chlorine additives don't dissipate.  Water suppliers sometimes use them because they are longer lasting than chlorine gas.  

In regards to chlorine gas, it's not necessary to allow the gas to dissipate prior to using it with your plants.  When we had our nursery in the Portland city limits, we used water straight from the tap, and the plants grew perfectly.  The water in Portland is very low in minerals and chlorinated with chlorine gas.  

Check with your water supply company for information about your water.  If uncertain about the water, use bottled distilled water instead.

Good growing!
Jacob Farin