Here is a great article by Alexis Petru of the Foster City Patch. It has been posted with permission of Alexis. Every spring, snowpack in the central Sierra Nevada mountain range melts and feeds the Tuolumne River. A portion of the river’s water is diverted and stored in Yosemite National Park‘s Hetch Hetchy Valley, which became a reservoir when the O’Shaughnessy Dam was built and flooded the valley in the early 1900s. Carried by gravity, the water travels 160 miles down to the Bay Area and into the homes of people like you and me who live on the San Francisco Peninsula.
The water from the Tuolumne River is “some of the purest, safest and best-tasting water in the world,” says the San Francisco Public Utilities Commission, which operates the Hetch Hetchy water system. The SFPUC tests water throughout their system nearly 90,000 times a year and reports that their water consistently meets or exceeds all federal and state standards for drinking water.
Nearly every resident of San Mateo County receives their water through the SFPUC’s water system. Ninety-three percent of this water supply comes from the Tuolumne River, stored at the Hetch Hetchy Reservoir and locally, along with rainwater, in the San Andreas, Crystal Springs and Pilarcitos reservoirs. The rest of the water supply comes from a variety of local sources—5 percent from groundwater and fewer than 2 percent from recycled water and locally operated reservoirs such as Bear Gulch.
Store-bought bottled water just can’t compete with the Peninsula’s excellent-quality tap water.
The National Resources Defense Council carried out a four-year study of bottled water and found that bottled water is not necessarily safer or cleaner than water from the tap. In fact, the environmental action group discovered that 25 percent of bottled water is just tap water in a bottle. After testing 1,000 bottles of 103 brands of bottled water, the group found that about 22 percent of the tested brands contained, in at least one sample, chemicals or bacteria in amounts above state health standards.
Bottled water also takes a heavy toll on the environment. Plastic bottles are made from oil, and the amount of oil and energy used to produce the plastic water bottles consumed annually in the U.S. would fuel a million cars for one year, according to Food and Water Watch. By contrast, the energy used to transport tap water from Hetch Hetchy to your home is minimal, as gravity moves water through the system. Because the water is so pure to begin with, there is also little energy expended to treat the water.
Bottled water creates 1.5 million tons of plastic waste per year, according to the National Resources Defense Council. While recycling your old water bottle is certainly environmentally preferable to tossing it in the garbage, it still takes energy and resources to re-manufacture the water bottle into a new product. Purchasing a reusable bottle and re-filling it with tap water eliminates the need for all those plastic bottles. Remember, it’s always better to reduce and reuse before you recycle.
And need I mention the financial cost of bottled water? Bottled water is expensive, and you’re already paying your city or water provider for high-quality tap water.
If you still feel squeamish about drinking water directly from the tap, use a water filter to further improve the water’s taste and quality.
There is a time and a place for bottled water—in your home’s emergency kit or when traveling in a place with a questionable water supply. But the Peninsula’s water supply is truly exceptional—pristine water from the Sierra Nevada snowpack. Choosing our tap water over bottled water also has a lighter impact on the environment. So grab your reusable water bottle, and get ready to take back the tap.
Alexis Petru is a San Bruno resident who coordinates environmental programs for San Mateo County. Her column appears biweekly on Fridays.
http://fostercity.patch.com/articles/take-back-the-tap-2
The contractor for the SFPUC's New Crystal Springs Bypass Tunnel & Pipeline project will be performing trench work the week of February 14th on Polhemus Road near the South Shaft site between Bunker Hill and Crystal Springs in San Mateo. 
