Where Does My Water Come From? Recently, I realized that in the quest to understand ‘the global water crisis’ better, I would have to start at home. I know that I have access to water 24 hours a day, that it is mostly clean and somewhat fluoridated, and that I have an individual home connection. But, I would like to know more. So I asked out loud, to no one in particular: Where does my water come from? And how does it get to my tap? After a little research, I found a wonderful resource by the Water Education Foundation. They have created a module that allows Californians to see where their water comes from through an interactive map. (http://www.water-ed.org/watersources/default.asp) Being a resident of San Francisco, I have been educated that my water comes from the Hetch Hetchy Project operated by the San Francisco Public Utilities Commission. But what I did not know is that the Hetch Hetchy reservoir, located in Yosemite National Park, was built on the Tuolumne River in 1923. John Muir, the well-known naturalist and preservationist, fought for many years against building a dam in this region. Since San Francisco was recovering from the 1906 earthquake, they needed water and electricity to support the rebuilding efforts. In the end, John Muir’s pleas failed and Congress (since it was federally-owned land) voted for the dam, allowing the Hetch Hetchy valley to be flooded. Though the reservoir supports 2.4 million Bay Area residents, and its water is transported 156 miles to San Francisco, many environmentalists are still asking for the reservoir’s restoration to its original pristine state: Public utilities act as the service providers for the water supply. They are owned by the state and usually manage distribution for a municipality or town. Most of the urban water supply (90%) in the world is provided by a public utility—of course the numbers for the rural population is quite abysmal, but that is another post! The utility’s job includes setting up a water supply system (like the Hetch Hetchy project), of which the water is sourced from an aquifer (underground) or lakes and rivers (surface water). They then purify the water through chlorination and disinfection, and finally transport it through underground pipes. Water is ‘assisted’ in flow either through water pressure pumps or by gravity. San Francisco, Boston, New York, and Portland are among the cities that receive minimally treated surface water because their water comes as runoff from snow melt which is quite pure, while 90% of U.S. residents get groundwater. San Diego, on the other hand, imports most of its water from other areas, specifically northern California and the Colorado River. Their distribution pipelines transport water a total of 300 miles! Since San Diego is a coastal city, and semi-arid, it may have issues with saltwater intrusion – where groundwater aquifers have become mostly salty due to ocean water and therefore undrinkable. It may be worth it to find out how clean drinking water gets to you. The chances are, you will end up learning something about the water supply that you did not know or would not have guessed. And that will eventually lead to better water practices like conservation and reclamation, which in turn adds longevity to the country’s water supply. Happy researching (and thoughts!), Shwetha Sridharan