Where's The Research?

Have you come across these in catalogs and magazines?  It's a dechlorinating garden filter, designed to "reduce free chlorine or chloramine at ambient temperatures."  The sales pitch is that watering plants with water from the tap (treated with chlorine or chloramine) is harmful to your plants and to soil microbes.  The problem:  I can't find any research, peer-reviewed or otherwise, that suggests this is true.  I can believe that salts used to treat municipal water may accumulate in the soil for a time.  Perhaps during periods of prolonged drought, when plants must be watered frequently, and rain isn't present to wash away those salts, plants may show signs of stress.  I don't know if I'd be able to tell the difference between drought-stress and presumed chlorinated-water stress.  Maybe it has more of an effect on houseplants -- they never get a flush from rainwater. 

If you know of any research-based evidence that watering from municipal supplies can harm plants, drop me a note.  I'd like to read it.


By the way, the dechlorinator is expensive -- $59.99.  Plus you have to replace the cartridges every growing season (twice a year here?), and those are 2 for $34.99.  There's an optional chlorine test kit for $15.99 to confirm whether or not the cartridge actually needs to be replaced.