The milky color is really air in your lines. If the milky appearance begins to disappear from your water starting at the bottom of a glass of water and clears by rising to the top of the glass within 1 to 2 minutes then your water is safe. Air in the water can be caused by different things. If PGUD or you have water turned off to repair a leak or some other reason, then that will cause air to appear in the water. Another event that causes air or oxygen in the water is the temperature of the water PGUD is treating. If the water is cold, it heats up a little when entering the water glass allowing the release of any trapped air. This is similar to boiling water on the stove. As the water is heating up, the air bubbles start appearing.