Ray, it depends greatly on the orchid being grown and the quality of the tap water being used.

B. nodosa can grow within a stone's throw of the ocean in Costa Rica, so is pretty tolerant of TDS. The commonly-available Phalaenopsis hybrids are also likely to be forgiving of less than optimal TDS, and as Subrosa said, it is important what ions make up that TDS.

I looked up the Hernando Co., FL reports online, unfortunately they do not list TDS (or electrical conductivity to estimate TDS). The data is probably available but it is probably necessary to call the utility department and ask. It looks like they have a half dozen or so sources in the county (likely wells). The one well I could find data for was just a raw well (not a public supply well, & without any treatment), it had TDS of 200 - 300 ppm, most of which was Ca and Mg.

It is still worth finding out what the local utility has measured after treatment for public supply.

Water quality is only one of the hot button topics here (so far, this is ok). If you want to see a really heated exchange, ask about pest control.:biggrin:

I hold all your contributions with high regard:bowing but some/many like me cannot afford the money, time nor energy to practice orchid growing at this level. I think, sometimes, this leads to discouragement for beginners and the misconception that orchids are difficult.

For the casual/beginner with garden center/HD/Lowes/TJ's/supermarket NoIDs, tap water is fine. Lower the TDS the better (augment with RO if you want).

If you have or plan to have species and named hybrids, start considering the discussions (this isn't the first one) on this board.

If you have super finicky orchids (PNG plants come to mind) use distilled/RO water (read discussions about micronutrients amendments).

And NEVER ever use soft water.

(And I do expect someone will have issues with something:roll:)

From what I gathered from researching last night online is similar to what you found. I looked at an adjacent county that pulls from the same aquifer and they vary from just under 200 to a bit over 200 ppm. I am thinking either mixing 50/50 with distilled water, or going 100% distilled or Reverse osmosis. What would you recommend?

Just one minor issue. Soft water is usually the cat's meow for orchids. Water which has been softened in a household water softener is loaded with sodium and is probably unsuitable for orchids.

---------- Post added at 04:52 PM ---------- Previous post was at 04:46 PM ----------

I would look at the orchids most sensitive to water quality which you're likely to keep. For me that's Oxyglossum Dendrobiums, and they need very pure water. For ease of care and to prevent costly mix ups, all the rest of my orchids except the aforementioned B.nodosa get the same water.

Mixing with distilled or RO water should work for most orchids. The Ca and Mg in the water tests that I saw would probably be beneficial for many orchids anyway (good, but at lower concentrations). Depending on your living situation, you also may be able to collect rain water, which is also low TDS (but not "pure" as you will see if you collect rain water! I filter mine so that it does not mess up the pump sprayer that I water with sometimes). The cost/benefit of an RO system has to be weighed; if you only have a half dozen plants, may not be worth it. If for some reason you also need RO water for aquariums and other hobbies, maybe it is worth it.

Just curious, and maybe I missed it, but what kinds of plants do you grow?

So far I have Dgmra. Pluto's Drummer 'Pacific Pink' , Phal. bellina var. coerulea x sib, Renanthera Kalsom 'Red Dragon', Wilsonara 'Pacific perspective', and a few variations of Onc. 'Sharry baby'.

I am new at this, but definitely have the bug. I am sure I will be adding more. Very grateful for all the help!!

I stand corrected.

Never ever use softened water.

Yes, the tolerance to dissolved solids does vary between plants, but there is no orchid that does not benefit from purer water.

I believe that switching to 100% RO and adding a small amount of a fertilizer designed for pure water has been the biggest help for my plants, as it is an easy way to approach their natural conditions.

The plants just look better, being nice and shiny, and seem to be "sturdier", and less susceptible to rots.


Ray Barkalow
firstrays.com