I am a 22 year old female and 6 months ago I moved into a house that is on well water. My hair has thinned a ton, and I”ve been to the doctor to test my iron levels, thyroid levels, and hormones (including testosterone). All the levels are normal. The dermatologist said I might have mild alopecia. I KNOW that is not the case. I had a beautiful head of hair up until I moved into this house. When I pull my hair back I can see through to my scalp. Should I get a Reverse Osmosis water filter? The doctors said that well water wouldn””””t cause hair loss, but I have found so much evidence that says otherwise. Please help me, the thought of loosing my hair is consuming my life.

The main thing to do is to first identify the cause of your hair loss.
There are many medical illnesses that can cause hair loss in women. The lab tests you have done are helpful, but usually they are all normal. One should evaluate you for chronic inflammatory diseases such as Lupus, as well. Have your DHEA level checked if this has not been done, but it is usually normal. As you mentioned, iron deficiency anemia can cause hair loss so you should check your ferritin level if you have anemia. You need to do more than look at your iron level if you have a microcytic hypochromic anemia. One should also check for Syphilis, but this is unlikely.

The next step is to have two 4 mm scalp biopsies done. They should be done in the area where you are loosing your hair and they should include intact hair follicles. One biopsy should be for vertical sectioning and the other should be for a lateral sectioning. These should be read by someone experienced in reading scalp hair biopsies such as David Whiting at Baylor.
This will probably give you the diagnosis.

You mention well water. The thing to look for here is heavy metals. These can cause hair loss, but usually this is not present.

Female pattern hair loss is the most common cause and the two biopsies will confirm or rule out this diagnosis. If this is what you have, you should then consider treatment options to include Rogaine for women.