Simple acidification might cause problems, depending on the chemical composition of the water; consequently I suggest that you measure its composition then pose the question again.

I am not sure a pH of 8.5 alone can explain skin problems from bathing water.

Can you share some more information about the water chemistry, geology there the well is and water treatment applied.

Alkalinity - 455 mg/l as calcium carbonate. Chlorides 364mg/l hardness 140mg/l TDs 708.

I still don't see this water is likely to cause skin problems.

Is it aerated before the supply system and if so does something precipate?

If not aerated could yo try to aerate a batch and record the pH before and after and look for precipation.

Its not aerated let me try your suggestions. Thank you

I am looking forward to see your results.