Is my city water hurting my orchids?
 

I've read a little into peoples experiences using tap water for growing orchids. How the common advice of it being bad for them is mostly not true, and many highly succesful growers in places with very hard water like Florida water with hose water daily. My waters hardness is apparently around 260 ppm, so after reading that, I didnt think about it.

Then I saw someone talking about it on here, and they mentioned that its not necessarily the hardness of the water thats important, but the actual chemicals and minerals. So I took a look at some reports for my city's water, and its got me a bit worried. I dont really know what all the chemicals are, but it looks like I have a lot of concerning things in excess.

EWG Tap Water Database | City of Laredo

Water hardness in Texas and city hard water information

Most of the orchids that people are likely to be growing are very forgiving of water quality. If you get into the sensitive high-elevation cloud forest species, you will do better with RO water. For the rest, they do just fine on city water. Don't worry about the lower-level contaminants that might be of concern for meeting drinking water standards. (If it's OK for YOU to drink it, its ok for the plants... and some things that really aren't OK for you to drink, like high nitrates due to agricultural contamination, also are no problem for plants... it's fertilizer) The organics look like there is contamination from solvents... manufacturing, and military. Again not great for humans but the plants don't care, and levels from a "plant" point of view are no big deal. Water your plants with it no problem, you might consider running it through a carbon filter or buying bottled water for drinking.

You can find the water quality report at your water utility. Take a look at that. Your first link is a non-profit trying to get your contact information.

I had a problem when I lived on the west coast. Some of the city wells had seawater seeping in so the sodium could be very high at times according to the report I found on line. I then boiled some of the water dry and tasted the residue. Yup, salt.

The Laredo water quality report is of little value, but that hardness page, showing a 260 ppm CaCO3 level, would have me a bit concerned.

No, it’s not fatal, but your plants would be happier with purer water.

Paphs should be fine with it... see notes from Brandon Tam of the Huntington Botanical Gardens mentioned in another thread. Other types might be fussier, but I have grown a huge variety of orchids with southern Caliifornia city water that is a lot worse for many years - and my local orchid friends grow a lot with water worse than mine. When you start to get hooked on Pleurothallids and some of the high elevation miniature Dendrobiums it's time to invest in RO. Until then, don't worry about it. When you water, water thoroughly - so that it runs through the pot, which flushes out buildup of hard water and fertilizer salts.

When we put up our greenhouse, we also had a fairly small R/O system put in, as the quality of our local water isn't great. Back when we were in Orange County, we used distilled water for our most sensitive plants. I can say that I've seen a dramatic improvement in terms of leaf tip browning in particular now that we've gone with R/O. I used to see a fair amount of this with Peristerias, Lycomormium, Paphinia, Huntleya, etc- very little since the H20 switch and I'm convinced that it's as a result of this change...

Those orchids are more sensitive to water purity and using RO makes sense for them. My Peristeria elata still grows fine with tap water; I can live with the dead leaf tips.

Catts, Oncs, Phals and terrestrials aren't that sensitive. 260ppm would be a dream for me.

Funny, enough, my elata always had pretty leaves. It was the other ones (pendula, lindenii, ephippium, guttata) that struggled...

My water is 800-1200ppm.

Wow, that seems insanely high. My tapwater hardness is around 75ppm... Are you able to use that water on any of your plants?

While it's not suitable for everyone.
We use catchment here for our domestic water.
We live in a high precipitation location in the middle of the Pacific, far from any contamination sources.
We use rainwater from our rooftop runoff as our water source.
From the roof gutters, it is piped to a 2k gallon catchment tank and stored.
Every time it rains, excess water runs out the tank's overflow.
I've never seen it drop more than a foot or so in the longest, driest periods.

In looking online I see that often people in arid areas also use catchment systems.
Not sure how well that works.
But, it does catch my interest.
I'd be leery of it in metro areas due to air pollution from cars, businesses and industry.
Had never worried about breathing it.
Now that I drink it, I do somewhat.
But, I sure like no water bill or added chemicals, and its being untouched by human hands.

I used to live in mainland northern tier metro areas with treated water piped to my home.
It never bothered my orchids.
And to my knowledge, it never bothered me.
Now that I drink rainwater, it's warm and wet enough that I just put them out on trees in the yard and let it rain on them, beats working at it.

I grew up on O'ahu and my mother in law had places in Kona and Kapoho. Miss home sometimes!

Back to itzi’s original question for a moment, with water of that hardness, the important thing is it’s alkalinity, that is, it’s resistance to pH change upon the addition of acids.

That’s important because high-alkalinity water - pH adjusted or not - will cause your media pH to increase over time, becoming more and more toxic to the plants.

Municipal water reports rarely offer that value, so getting the water tested is a good idea. The J.R.Peters Lab will give you a complete test for $44. Not cheap, but considering out investments in our collection, probably a worthwhile investment.

I collect rain. I mix tap into rain so I don't need to buy calcium supplements. I use my high tds tap water from time to time when I must water and don't have much time. It doesn't seem to bother most Catts, Phals, Paphs, Phrags nor Oncs. The Phrags are in S/H and I flush them thoroughly.