AR5 concluded that climate change was projected to reduce water quality . SR1.5 assessed with low confidence differences in projected impacts under 1.5℃ compared with 2℃ of warming . In addition, SROCC reported water quality degradation due to the release of legacy contaminants in glaciers and permafrost  . The AR6 WGI Report does not explicitly mention water quality issues.
IPCC
Climate Change 2022: Impacts, Adaptation and Vulnerability
IPCC Report