Drinking water on Long Island comes from underground aquifers. The quality of this abundant supply must be protected, and we must use our supply wisely. The best way to protect our groundwater is to not pollute our aquifers.
This section of our website provides information and offers tools for you to become “groundwater guardians” and help protect our most precious natural resource.
About our Water Source
View Water Cycle
All of the water we supply to you comes from beneath the ground and is referred to as groundwater. The water is stored beneath the ground in a sandy, geological formation known as the Aquifer System. Water in the Aquifer System originates as precipitation (such as rain and snow), which slowly percolates down through the soil and into the aquifers. There are four primary formations which are layered and make up the Long Island Aquifer System. From the shallowest to the deepest, these formations are:
Glacial – Contains the newest water to the groundwater system. The Authority has 268 wells drawing from this portion of the system. Virtually all private wells draw from the Glacial Aquifer.
Magothy – is the largest of the three formations and holds the most water, much of which is hundreds of years old. There are 329 Authority wells drawing from this portion of the aquifer.
Raritan – a clay layer that separates the Magothy and Lloyd aquifers. Some portions of the Raritan contain permeable, sandy formations that hold enough water to pump from. The Authority has 3 wells in the Raritan.
Lloyd – is the largely untapped layer which contains the oldest water, some of which has been held in the Aquifer System for more than 5,000 years. The Authority has 3 Lloyd wells.
The total depth of the Long Island Aquifer System is shallowest on the north shore (approximately 600 feet) and deepest along the south shore (approximately 2000 feet).
Healthy Lawns, Healthy Water
How Big is your Water Footprint