You have to find a lab that tests locally or somewhat locally. Just start calling around, that’s what I did. People know people who know people. Eventually you’ll get to someone that can help. Takes some effort though. Took me a few weeks as most labs process commercial size volume vs individual samples. Samples must be taken and returned same day usually. The labs usually either give out the sample jars free, or charge a minimal fee. The usual test is for total nitrates, and a second for total coliform bacteria. But there’s also lead, and other chemicals they can test for all at additional fees. Not many wells around here. Think I’ve inspected and sold 3 in the past year, but it’s still extra revenue. No licensure required here, just make sure it’s not required in your area (probably not as it’s filling a jar with water, really). Just make sure when you sample, you let the water run for a good 2-3 minutes before you fill the sample jar as you want fresh out of the well water, and not stuff that’s been sitting in the pipes for who knows how long.