Milky white water, also commonly described as cloudy, hazy, soapy or foamy, is almost always caused by air in the water. One of the many properties of water is its ability to dissolve gases, including air. Sometimes the air escapes from the water in the form of many tiny bubbles; this gives the water a milky white appearance.
To see if the white color in the water is due to air, fill a clear glass with water and set it up on the counter. Observe the glass of water for two to three minutes. If the white color is due to air, the water will begin to clear at the bottom of the glass first, and then gradually will clear all the way to the top. This is a natural phenomenon and is completely normal; the water is safe to use. This can happen when the water gets cold, or whenever the water has been turned off for repairs. Cold water holds more dissolved air then warmer water. As the water moves through the water mains in the street and the pipes in your house, it begins to warm up and lose some of its ability to keep the air dissolved. However, because the water is under pressure in the pipes, the air remains in the water. When you relieve the pressure by opening the faucet and filling your glass with water, the air is now free to escape from the water, giving it a milky appearance for a few minutes. This same set of circumstances is also why you will often see that your hot water is cloudy.
Another way for this milky white water to form is after your water utility has worked on a water main or you have had work done on your plumbing. When the water is shut off, air can get into the water main or your pipes. When the water pressure is restored, some of that air dissolves into the water. When you again relieve the pressure by opening the faucet and filling your glass, the air is now free to escape from the water thus giving it a milky white appearance for a few minutes.
If your water is cloudy or milky white in appearance and it does not clear in a glass after five minutes, you should contact the Public Works Department at 708-503-8200.