Wilson wrote:
I have a drilled well that goes down 220'. When it was drilled in
1995, the pH that came back with the first water test was 7.0,
perfectly neutral.
Over the years, I've had some plants begin to give me problems that
took a while for me to notice developing as I thought it was just a
year to year change in local conditions.

This year, in the spring while natural rain was sufficient, I remember
remarking to my wife, 'Go look at the cucumbers if you want to see
some nice dark green foliage.' During the past few years, my cukes
have dropped off in production and the leaves are more yellow than
dark green. This year we made no cucumber pickles and barely had
enough for sandwiches.
I maintain a totally organic garden making compost & using some aged
hen manure that is mixed with softwood chips in their bedding, so I
doubted that the yellow leaves came from a lack of nitrogen. Also,
these are raised beds (3' x 10' x 10") and have good drainage.

This year, after testing the mother-in-laws water and finding a level
of coliforms higher than zero, I retested my own. I found that my pH
had risen to 8.7.

But before testing, as the springs rain slowed, I began using a 'wand'
waterer on my hose which puts down a lot of water fast. Within a
couple of weeks, I noticed that the cukes were yellowing, my zukes
wouldn't set fruit, indeterminate tomatoes failed to achieve their
usual height and her garlic shriveled up and disappeared.

I sifted the garlic bed and saved all the bulbs I could find. In
August, we got 18" of rain & I stopped watering with the well water.
New garlic sprouted from the tiny bulbs I missed and are still
growing lushly.
I'm going to switch to rain water next year. However, I can't find
anything when I search on the effects of high pH water on plants. Nor
have I any idea why my pH would change. Anyone else seen this happen?

I have no idea why the pH of your well water changed but I doubt you can
alter it. I also doubt that the water is doing much directly to your plants
but it may be altering the pH of your soil which will make a difference.
The effect of high pH in the soil is to lock up some minerals by making them
less soluble, this produces deficiencies in plants. A pH of 8.7 is quite
high for a garden soil, not that it is certain your soil will necessarily be
that high just because you are using water of that pH.

You should test the pH of your soil before going any further. I find the
best kind of test is using dye indicators, a kit will cost maybe $20 and
will do many tests. These kits are sufficiently accurate and reliable for
the purpose, cheap electrical probe systems are not. I would stop using
that water except in emergencies as it will slowly deposit minerals in your
soil that will eventually raise the pH of the soil. For most plants (there
are exceptions) a pH of about 6-7 is desired. If your soil's pH has in fact
risen much above 7 you may have to amend it to lower it again or stick to
alkali tolerant plants.

David