That EPA site more than obtuse. It's impossible to find a company that has a service that will mail you a container, have you add the water to it, then send it back to them to have them test it.

The closest I found was: https://www.meritlabs.com/sample-bottle-order but there are not even prices and it appears that you have to be more or less an industry expert to even fill out the order form.

Someone should make a startup like 23andMe but for water. Lots of us would pay $500 to have water accurately tested. Especially if the data could be aggregated and made pubic.