5 largest Unfiltered Water Systems

New York City was relieved yesterday when the EPA announced that they will not have to spend $8 billion to build a water filtration plant. The city will be exempt from filtration requirements until 2017. Read more about this announcement in the NYtimes.

This announcement got me interested in just who are the largest water systems that skip the filtering process in treating raw water in the US. Here are the 5 largest unfiltered water systems in the United States.

1. New York. This is the largest water system in the country operating under an approved filtration avoidance waiver. About 90 percent of the 1.4 billion gallons used by the 8 million New York City residents each day comes from reservoirs in the Catskill Mountains, 120 miles north of the city. The remaining 10 percent is drawn from closer reservoirs and will have to be filtered by a $2 billion filtration plant under construction in the Bronx.

2. Boston. Boston's unfiltered water comes from the Quabbin Reservoir, about 65 miles west of Boston, and the Wachusett Reservoir, about 35 miles west of Boston. The two reservoirs combined supplied an average of 220 million gallons per day in 2004. The reservoirs provide drinking water for nearly 2.5 million people. 75% of the total watershed land for both the Quabbin and Wachusett Reservoirs is protected and cannot be built on.

3 San Francisco. Hetch Hetchy Reservoir, located in Yosemite National Park, provides approximately 85 percent of San Francisco's total water needs.The water travels 167 miles from the reservoir to 2.4 million customers in San Francisco, San Mateo, Santa Clara and Alameda counties.

4. Portland, Oregon. The Bull Run watershed has been a City of Portland water resource since 1985. The watershed is east of downtown Portland and is reserved solely for producing drinking water. The Portland water system serves drinking water to more than 800,000 Oregonians, over one-fifth of the population of Oregon. Two reservoirs, Bull Run Dam 1 and Bull Run Dam 2, combined supplied an average of 99 million gallons per day in 2006.

5. Tacoma, Washington. Tacoma uses the Green River to supply 72 million gallons of water each day to an estimated population of 302,392. Tacoma Water can supplement its Green River supply with water from seven wells.