I bought my first parcel thinking a 15-gallon-per-minute well test was solid proof of water security. What I didn't understand then is that yield tests are typically run for four hours, sometimes less. They tell you nothing about long-term aquifer behavior, static water level trends over a decade, or how many neighboring wells are pulling from the same formation.
After I got my water law certification and started helping others through purchases, I pulled historical driller logs from the state engineer's office on properties before clients even made offers. In my region, static water levels on some formations have dropped 40 feet in 20 years. A well that yields 15 GPM today might be marginal in 15 years depending on how saturated the formation still is.
The well yield number is the one data point buyers fixate on, and it's probably the least predictive of the three or four things you should actually check.
Anyone else pulling aquifer trend data from their state engineer's database before closing, or is that still considered overkill in your region?