Hello and hope you are doing well.
Environmental triggers for allergic reactions like changes in weather, temperature and water sources are difficult to avoid, but being aware can help you take adequate precautions. You can check to see if the piping has any allergies. Also, try distilled water, see if this is causing reactions. If the present antihistamines are not very effective you can consult your doctor for long acting ones.
Hope this helped and do keep us posted.
i've had it for 4 years, with no "cure". the only thing that is amazing to me is that i'm currently taking accutane & the itch-after-water is almost completely gone. almost makes me have anxiety about finishing my accutane bc i'll go back to itching like crazy. :(