Cold recovery technology in drinking water systems was studied to see if it affects water quality. Three systems were tested for 38 weeks: one with cold recovery, one without, and one control. Results showed no significant impact on water quality, with similar bacteria levels and diversity. Only when the temperature difference was over 9°C, some specific bacteria increased. Biofilm in the system with cold recovery had higher ATP levels and different bacteria, but this didn't affect water quality. Overall, cold recovery did not change bacterial water quality, but longer studies are needed to fully understand its effects.