For those who don't already know this is a pic of Brandon Tam. These pics are from the greenhous that he takes care of. He has assistance of course, but it is his charge. They say they have about 900 species and over 2,000 hybrids there at The Huntington.
Their collection is grown on well water I think about 300 TDS. Last year the wells went dry and they had to go with straight tap water about 700 TDS. They do not use RO at all.