Due to the perennial spread of bad information, folks have come to equate “moisture” with “root rot”, and it’s untrue.

Unlike terrestrial plants that do most of their respiratory gas exchange through their leaves, epiphytic orchids have evolved to do much of that through their roots. So let’s think about that in relation to potting media and watering:

When we water, most pours right through and some is immediately absorbed by the roots and the potting medium. There is a third fraction that is pertinent - that which is held in-between the particles by surface tension.

If the void spaces in the medium are small, either due to the use of too fine of a medium or because it has compacted with age and decomposition, water can completely fill them, which cuts off air flow to the roots, suffocating them. Then they die and rot. If the void spaces are large, however, water only fills around the contact areas, and open pathways for air movement and gas exchange are still present.

So... to me “overwatering” is a misnomer. It should be “under-airing”. I really believe the myth that “orchids must dry out between waterings” is based upon a misinterpretation of observation. If you have a poor medium that stops airflow to the roots when watered, letting it dry opens up the structure again, letting the roots “breathe”. Bad medium, not bad water.