For anyone who hasn't heard why your tap water is looking so cloudy these days, it's because of a temporary increase in the air in the water, according to the San Francisco Public Utilities Commission, which handles the distribution of water from the Hetch Hetchy Reservoir in the Sierra Nevada Mountains.

Here's what's happening, according to the SFPUC:

Customers are receiving water from local reservoirs because of maintenance work on the Hetch Hetchy distribution system.

The water is being treated at SFPUC's Sunol Valley Water Treatment Plant, which is increasing the amount of air mixed in the water, causing the change in its appearance.

The cloudy or milky-white appearance does not affect the quality of the water, the commission says.

"The SFPUC's water continues to meet all state and federal regulatory requirements for water quality," The SFPUC says. "This temporary change involves the appearance of the water only."

The cloudy look will dissipate when Sierra Nevada water supplies begin to reach the Bay Area after system work is finished sometime in February, according to the commission.