云样自来水

有时候水龙头里流出的水是云样的，看上去象奶白色的碳酸饮料，而且过一会就变得清凉透彻了。这是因为水中溶解的空气释出为大量小气泡造成的。从Massachusetts Water Resources Authority抄了个不错的解释如下：

Why does my tap water look cloudy this winter?

By Massachusetts Water Resources Authority

Question: The hot and cold water from our kitchen sink sometimes comes out very cloudy. If we leave the water in the container, it then clears up quickly and the cloudiness disappears. Should we be using this water, even after it turns clear?

Answer: Cloudy water, also known as white water, is caused by air bubbles in the water. It is completely harmless.

It 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 the reservoir which is very cold and warms up during its travel to your tap. The air that is present is no longer soluble, and comes out of solution.

In addition, once water from our reservoir enters the transmission and distribution pipes, the water is pressurized. 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.