All About Water Pressure

The above picture shows how water pressure is maintained and why it will vary depending on where the service connection is. In a typical water system such as the one operated by the Suffolk County Water Authority, water is pumped out of the ground from wells into our distribution system, which is a network of buried pipes with customer services connected to it. Also connected to the distribution system is an elevated storage tank that typically holds around a million gallons of water high in the air. The well pumps are turned on and off so as to keep the tank full of water.

As you can see, if the tank is full of water and the customers are all connected at points below the water level in the tank, then when a customer opens a faucet, water will flow out. To further your understanding, visualize a hypothetical house that is connected at a point that is above the water level in the tank. In this case, the customer would be unable to receive any water because water does not flow "up hill".

The height of water determines its pressure. The measure of how much pressure a customer has in their house is simply the vertical distance between the faucet in the customer's home to the water level in the tank. The greater the height, the more pressure a customer has. The basic formula is 2.31 Ft of water = 1 Pound Per Square Inch (Psi). As you can see from the picture, customers that live in higher elevations will have lower water pressure than customers at the lower elevations because they have less distance between them and the water level in the tank. The scales on each side of the picture show what the water pressure is at the various elevations above sea level. The topography on Long Island varies from sea level all the way up to approximately 400 feet above sea level.