A release from the city of Sandusky -
Residents may have recently noticed their tap water is cloudy or milky, but clears within seconds.
This cloudiness may be caused by water in the pipes being under a bit more pressure than water in the glass, but is more likely due to tiny air bubbles in the water. Like any bubble, the air rises to the top of the water and goes into the air above, clearing up the water. Cloudy water, also known as white water, is caused by air bubbles in the water and is completely harmless.
This usually happens when it is very cold outside because the solubility of air in water increases as water pressure increases and/or water temperature decreases. Cold water holds more air than warm water. In the winter, water travels from Lake Erie, which is very cold, and warms up during its travel to the tap. Some of the air that is present is no longer soluble.
Also, water pressure has something to do with it. The water in the pipes is pressurized to a degree (which helps to get the water all the way from the water tower to your home). Water under pressure holds more air than water that is not pressurized. Once the water comes out of your tap, the water is no longer under pressure and the air comes out of solution as bubbles (similar to a carbonated soft drink). The best thing to do is let it sit in an open container until the bubbles naturally disappear.