New York City has spent nearly $5 billion in the last decade protecting water customers from two little parasites, cryptosporidium and giardia. These protozoans will cause gastrointestinal distress for many people and more serious—even fatal—problems for those with weakened immune systems.
In the city’s east-of-Hudson Croton watershed, where development has encroached on watershed land, federal regulators forced the city to filter the water; hence the $3 billion Croton filtration plant that recently opened.
The city’s larger and more distant Catskills and Delaware watersheds have been better protected, so there the city was required to merely disinfect the water with a plant that cost $1.6 billion. Located in the Westchester County town of Eastview, the high-security UV disinfection plant is considered the largest water treatment facility in the world.