Well Water Analysis — OK for orchids?

[My Green Pets]

Good day all,

Below are some values from a recent analysis of well water that I would like to use for my orchids. Some minerals and metals are shown to be at 'very high' levels, and I was wondering if you pros had any insight on how that might affect my plants.

Values in parts per million (ppm).
L=Low, N=Normal, M=Moderate, H=High, VH=Very high

Nitrate Nitrogen: 0.7 (L)
Phosphorus: 0.26 (N)
Potassium: 1.73 (L)
Calcium: 98.5 (VH)
Magnesium: 44.74 (VH)

Sodium: 34.06 (L)
Chloride: 10 (L)
Sulfate: 0.42 (L)
Boron: 0.11 (L)
Zinc: 0.05 (L)
Manganese: 0.04 (L)

Iron: 1.04 (VH)
Copper: 0.01 (L)
Carbonate: 0 (L)
Bicarbonate 579.5 (H)

pH: 7.4 (N)
Conductivity: 0.83 mmhos/cm (M)
Total dissolved solids: 528 (M)
Sodium absorption ratio (SAR): 0.71 (L)

Thank you as always for your expert advice!

[james mickelso]

Your main concern with the water is the pH value and the high Calcium carbonate which is hardness. I have around 350 hardness as calcium carbonate here in SoCal. You can buy some water from the RO water dispensing machines in front of WalMart or grocery stores and if they don't have any buy a small RO unit that hooks right up to your sink. Then blend it 50/50 to decrease the hardness a. You can use citric acid or phosphoric acid to lower the pH too. Get some pH strips from a pool supplier or a pet store to test your water's pH.

[King_of_orchid_growing:)]

The question has to be honed in a bit more than just whether the water chemistry is good enough for all/any orchids in general. What kinds of orchids are we talking about?

If you're talking about orchids that naturally come from areas where there is an abundance of limestone, then your water is fine.

If you're talking about orchids where they prefer more of an acidic environment, and the amount of CaCO3 can be disruptive for their physiology because it is just not present in large amounts where the orchid grows, then you've got a problem.

There are also a good number of orchids that do not grow in limestone rich areas and do not grow in acidic areas with low CaCO3, and from what I see, the water chemistry doesn't appear to be of any large concern to these groups of orchids.

Get what I mean?

So, if you want to narrow it down to what orchids you are particularly concerned about, then we're talking.

Although, if you want to use RO/DI water, it's up to you too. You just have to understand that for whatever major, minor, or trace minerals that are insufficient or missing, you need to accommodate for that.

I don't know how you would be able to find this piece of information out, but if you are able to do some research and find out why the mineral contents in the water are the way they are in accordance to the geology/mineral composition of the rocks in your area, I believe you can start to make the connections as to how it could relate to orchid growing.

[Orchid Whisperer]

I am less concerned about the pH and more concerned about total dissolved solids. TDS in the 500 ppm range is likely to be a problem long-term; it should be 200 or lower, and much lower is better. If you have a bunch of plants and collecting/storing rain water is not an option, then consider an RO unit.

With high TDS, Ca and Mg, I will take a guess you are in Central Kentucky?

---------- Post added at 04:16 PM ---------- Previous post was at 04:10 PM ----------

BTW, K.o.o.g. is right, some orchids will be more tolerant than others re: the pH and Ca and Mg content. My Bletia patula would likely be fine with it, a Disa would probably hate it pretty fast.

[My Green Pets]

James, KoOG, OW, thanks for your thoughtful replies.

If I understand correctly, some orchids will love this water, some won't mind it, and others will detest it.

In that case, I suppose that once again, it's time to experiment.

The well is 150 feet/46 meters deep. The water is free, so I would like to take advantage of that instead of spending money on RO/DI.

And OW, I'm in the western part of the state, just a few miles from the mighty Ohio River.

As for my orchids, there is a little button in the heading area of each of my posts that, when clicked, will open up an accurate list. Only thing is, it won't work in Tapatalk:

[james mickelso]

If you are growing terrestrials like paphs or bletillas then pH and CaCO3 is a concern. But most orchids most of us grow are epiphytes and as such are watered with rain water which seldom has any TDS or Ca or Mg at all. The only phosphorus or potassium they get comes from bird poop and dust blown in from afar.

[King_of_orchid_growing:)]

Looking through the orchids on the list, I don't perceive that there's anything to worry about. I think that the likelihood that your orchids would be hurt by the chemistry of your well water is pretty low.

Just keep an eye on your Oncs and see how they react. Everything else, I'm far more certain that there wouldn't be any major issues that'd come out of using the well water.

[Orchid Whisperer]

If you can catch some rain water an blend in with your well water, the blend would be lower TDS but still provide some beneficial Ca and Mg.

[Hiester]

Interesting information in this topic. What I am wondering is if anyone has ever been able to find the precise mechanism used by water filters that are installed in refrigerators for the ice maker and water dispenser? I have a Frigidaire™ side-by side with the PureSource II™ filtration. I have been able to find the list of contaminants supposedly removed by the filter, but I cannot find specifics about the method or mechanics used to perform the filtration. My tap water from the municipal supply is reported to be between 30 and 80 p.p.m. dissolved solids, which seems to be good considering what others report about various water supplies around the country, so I don't worry much about using my tap water to supply my orchids. It would, however, be nice to know what the PureSource II actually does to the water. My municipal supply is all surface collected (about a dozen different mountainous sources) and sanitized using ozone in lieu of chlorination unless there's been excessive rainfall. I can always tell when the chlorination has kicked in from the change in smell.

[james mickelso]

Ozone is a good disinfectant as long as there is no contaminants. Virus can hide in the contaminants and miss being disinfected. Same with UV disinfecting. There is no residual disinfection carried downstream in the water supply, so any contamination like a leak in the pipeline to your house carries the risk of pathogenic contamination. Your filter works on a permeable membrane whose pores are small enough to filter out harmful bacteria/viruses/metals leaving good tasting clean water. At such a low TDS in the supply the filter doesn't have to work very hard. The filter acts as an RO unit.