I forget what the range the pool pH drops covers, but I don't remember ever seeing any that cover a 5-7 range. Most plants are right in the middle at about 6.0. But if it covers the range that your meter said that it's reading, that should at least corroborate the reading. What comes out of one persons well isn't always the same as someones else. When it comes to using well water, there can be many minerals and/or micro-organisms in it. And some people don't even filter their well water sufficiently. Those are my main concerns with it, and pretty much hard for me to assess from here.
Some Articles on Water Quality
Hydroponic H2O: Water Quality and Treatment
The Dynamic Nature of Water- Part I
The Dynamic Nature of Water- Part II
But I would use a UV light to kill pathogens and fungi, then run it through a good filtration system (1 micron). A 1 micron filter should be small enough to even catch spores. In the long run a filtration system will be much more cost effective than buying bottled water. The machines that sell water that's dispensed into your own container/s are OK, but they don't usually keep up with filter changes. so the water quality will vary from one machine to another. But regardless of water quality, you'll need some hydroponic pH adjusters.