RO or distilled or ZeroWater?

[Lucille]

First, I'm going to get the facts, because all local water systems can differ. My water might be perfectly OK for the orchids. I sent off for a TDS meter which should be here Friday.
I have set up my plant area and I water in place. I could take the plants to the sink and flush water through the media but not often, I am a senior and it is difficult for me.

At what level, in your opinion, of dissolved solids reported by the TDS meter, should I consider looking into a treatment method to remove those solids before watering?

[Ray]

1) TDS meters are notoriously inaccurate, so while it's a great little tool for judging "this time" versus "last", it is not a particularly good tool for "what is the actual contents".

2) The limits on actual dissolved solids content vary, depending upon the plants grown, and upon what's in the water.

That said, I have never had issues with phals, catts, and paphs with 250 ppm water, with fertilizer added to that. However, ALL orchids benefit from the use of pure water, to which a very small amount of complete fertilizer has been added.

Without a doubt, an RO system is the most economical way to provide good water for your plants.

[Orchid Whisperer]

Water in Texas can be notoriously variable in quality, from good to bad. If you live in oil country, "salt domes" in the local geology can greatly affect wells, springs, even rivers if the domes are near land surface.

If you are on a public water supply, they probably monitor TDS, and that information should be available to the public. Try asking your water department, see if they can provide you with current and historic data. Electrical conductivity (EC) data can be used as a proxy for TDS; all TDS meters simply estimate TDS based on EC measurements.

If you are on your own well, and your TDS is over 200 to 250 ppm, consider a countertop RO unit. Ray used to sell them, possibly still does.

[Lucille]

I decided a counter top RO was probably a good idea even before getting the tds meter, because I really want to avoid taking the plants to the sink and flushing very often, so I have ordered some stuff and I'm going to put one together .

[jkofferdahl]

I'd absolutely go with RO over distilled.

[Fishkeeper]

RO is gonna be cheaper long-term and will use way less bottles, but there's no functional difference between it and distilled as far as the plants. Both should have nearly 0 TDS.