The pipe lines for tap water delivery is pressurized, therefore, it is necessary to install depressurization valves (breathing valves) at selected points to prevent over pressurization. This means air will be sucked in to stabilize pipe line pressure, therefore, adding air bubbles into the tap water system. The air bubbles make the tap water look whitish, but as they escape, the water becomes clear again. This has nothing to do with the water quality, please don't worry.