Annual maintenance of system will cause bubbles in tap water
By: Katie Worth
January 4, 2009
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| Bubbly water: Due to annual routine maintenance on the Hetch Hetchy water supply system, area tap water may appear cloudy during the month of January. (AP file photo) |
There is a forecast of clouds for January — but this is for tap water.
The San Francisco Public Utilities Commission is warning its customers across the Bay Area that their tap water may come out cloudy for a few weeks, while the agency does its annual routine maintenance on its Hetch Hetchy water supply system.
The milky color is the result of microscopic bubbles in the water, and does not affect the quality of the water, according to SFPUC spokeswoman Betsy Rhodes.
While the maintenance is going on — starting Monday and concluding no later than Feb. 1 — the supply of water from the Sierra Nevada will be shut off so one section of the supply route can be inspected and repaired, if necessary, she said.
In the meantime, the water supply will come entirely from the Bay Area’s reservoirs, including some lakes in the East Bay and others on the Peninsula. Because of the increased demand, water must be run through the Sunol Valley Water Treatment Plant more quickly than usual.
Though this process does not damage the quality of the water, it does mean the microscopic air bubbles that accumulate in the water during the treatment process do not have time to dissipate before entering the distribution system, she said.
The water comes out of the tap that milky color, though it clears up if left to sit for a few moments, she said.
The problem tends to affect East Bay and San Mateo County customers more than San Francisco’s, because San Francisco gets most of its water during this time from the Peninsula reservoirs, rather than the East Bay’s, she said. Also, San Francisco is “the end of the line,” so the air bubbles have had more opportunity to dissipate by the time the water supply reaches San Francisco, she said.
Though this period of maintenance has occurred seven times in the last nine years, it still takes customers by surprise, said Justin Ezell, superintendent of water utilities for Redwood City.
“We get a lot of calls and inquiries from people wondering if it’s safe to drink, and why it’s cloudy. It’s something that happens every year but people tend to forget that it happened the year before and what it’s caused by,” he said.
Last year, he said, about 22 people called to inquire about milky water.
About the cloudy water
WHAT: For a few weeks, some Bay Area residents will notice milky or cloudy water coming out of the taps. The water will clear up after sitting for a few moments.
WHEN: The routine maintenance will begin Monday and will be completed no later than Feb. 1.
WHY: The Hetch Hetchy water supply will be shut down for a few weeks for routine maintenance. During this time, water will come from Bay Area reservoirs, and local water treatment facilities will be sped up. Though this increased production does not affect the water quality, it does prevent the microscopic air bubbles in the water from dissipating before water is distributed.
Source: San Francisco Public Utilities Commission
