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

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).

Long Island Commission for Aquifer Protection (LICAP)

The Long Island Commission for Aquifer Protection (LICAP) is a bi-county entity formed to address both quality and quantity issues facing Long Island’s aquifer system and to advocate for a coordinated, regional approach to groundwater resources management.

Interactive Water Model

To check out this Interactive Water Model to learn more about the water cycle, click below.

Open the Interactive Water Model

How big is your footprint?

Have you ever wondered just how much water you actually use?

A tool called the Water Footprint Calculator, developed by GRACE Communications Foundation, lets you estimate your water use and helps you identify ways to reduce your overall “water footprint”.

Try the Water Footprint Calculator

Reducing your overall water footprint is important because freshwater resources are being threatened. Only 3% of all the water in the world is freshwater, and of that 3%, only 1% is accessible and useable by humans.

Virtual Water
The Water Footprint Calculator relies on the concept of virtual water – the water it takes to create the products and energy we use – to help estimate your water footprint.

Where do we use most of our water?

1. What you eat and drink accounts for most of your water footprint because almost one third of all water withdrawn in the United States is used for agriculture.
2. A typical household uses thousands of gallons of water each year for things like toilets, showers and lawn watering.
3. The average family of four indirectly uses hundreds of gallons of water per day if their electricity is produced by power plants that rely on outdated cooling water systems. Such plants account for nearly half of all water withdrawn in the United States.
4. It takes a lot of water to make the consumer goods and services that you use and buy everyday.