Water Quality: Hardness, pH, TDS. Where to draw the line?

[Orchid Whisperer]

Originally Posted by King_of_orchid_growing:)

TDS of the water will usually not be a significant factor until you start getting into orchids that are more sensitive to high amounts of calcium carbonate in the water such as Pleurothallids or Disa.

I would agree, if you have a good idea what constituents make up the dissolved solids. If you are in a coastal region, or in the gulf coast area where salt domes are common and can affect well water quality, then sodium may be a significant problem, and more of an issue for orchid health. If I lived in northwest Georgia, or parts of up-state North Carolina where limestone is common, then the TDS could be elevated due to calcium carbonate, but not be a concern for most orchids.