[3] (The city's third supply system, the New Croton Aqueduct, has a separate treatment plant.

Mayor Michael Bloomberg created research groups between 2004-2006 to decide the best and most cost-effective ways to modernize the city's water filtration process, as a secondary stage following the existing chlorination and fluoridation facilities.

The UV technology effectively controls microorganisms such as giardia and cryptosporidium which are resistant to chlorine treatment.

[5] The city staff determined that the cheapest alternatives to a UV system would cost over $3 billion.

In response to this finding, Bloomberg decided to set up a public competitive contract auction.