I drink the tap water whenever I am there and it is fine.
Tap water is safe to drink practically anywhere in Poland, except in a handful of small rural communities where shallow private wells have been contaminated by agricultural activity, usually nitrate-containing fertilizers.
There is a lot of concern about drinking tap water among Poles. However, as research
shows, these concerns are unjustified. Tap water in Poland meets all standards since it is
constantly monitored by the water companies and all relevant health services."