“First, the chlorine or other chemicals used to treat the water can further damage tissue in the wound, adding to skin breakdown and inflammation. Second, there is risk of infection of the wound with continued exposure to water, and this risk is increased more if swimming in lake, river or ocean water.”
Article source: https://www.huffingtonpost.co.uk/entry/doctor-pool-safety-advice_uk_6a58ad68e4b07a7875d1d795