Allergies can be a problem, also the transport vessels (pipes)can be a problem. It doesn't matter how good the water is leaving the treatment plant as it can be fouled rapidly in the pipes...
I paid about $2000 to have the water tested at my house. This meant testing the water at each spigot (faucet), inside the house as well as the outside... That is the only way to truly know what water quality that you are receiving.
Broken pipes even far away from your house can introduce bad stuff also...
With old pipes, whether inside your house or under the streets to get to your house, you should always allow the water to run a couple of seconds first as heavy metals tend to congregate at the spigots (or faucets).
While all of FL has the same aquifer, water is not always used from the aquifer. Sometimes it comes from rivers and such.
Well water (aquifer) can vary in quality depending on area, due to waste (animals, dumps, old factories), minerals (sulfur, etc.), fertilizers, pesticides (old orange grove areas especially...).
I am glad that you have resolved your health issues by finding the culprit!