Groundwater Movement and Protection

This video describes where the water in a well comes from and how it moves.

The water cycle moves water through the environment. As water falls to the earth as precipitation - either rain or snow - it may run off into streams, lakes, rivers or bays. Water will evaporate from these surface water bodies. Water that evaporates, can later condense (called condensation), forming clouds that may produce rain or snow.



Groundwater and surface water are interconnected. When the water table rises above the land, groundwater discharges to the surface and becomes surface water. Also, if the water table drops, surface water can recharge the groundwater. If you've ever been swimming in a lake or pond and felt a "cold spot", this cold spot could be groundwater discharging into a lake or pond.



An aquifer is an area of underground soil or rock that is filled with water. An aquifer is capable of supplying water to a drinking water well. Throughout New England there are two types of aquifers used to supply drinking water. These two types of aquifers are sand and gravel aquifers and bedrock aquifers.



The water table is the top of the groundwater. It is the boundary between the saturated and the unsaturated zones. The water table rises and falls according to the time of year and how much rain or snow we receive.


Groundwater is recharged from precipitation - either rain or snow melt. Groundwater recharge occurs on areas of the earth's surface



Groundwater moves from recharge areas to discharge areas. When the water table rises to the land's surface, groundwater discharges into surface water. Groundwater discharge areas include wetlands, lakes, ponds, rivers, springs, and the ocean.



A well is a circular hole that extends into the earth until it reaches the aquifer. Wells pump water from the aquifer into our homes. Three basic well types are common throughout New England: dug, driven and drilled wells.


Septic systems treat household wastewater. Septic systems that are not maintained properly can be a source of groundwater pollution. Pollution from septic systems include nitrates and bacteria. Also, if we pour hazardous chemical down the drain and into the septic system, those chemicals can pollute the groundwater.

Nitrate is a potential groundwater pollutant that occurs naturally in the environment and is also a breakdown of human, animal, and pet waste. Nitrate is an important plant nutrient that is also in fertilizers. We use fertilizers on our lawns and gardens to help our plants grow. Farmers use fertilizers on their crops. Excess nitrate in drinking water can cause health problems. It is important that private wells are regularly tested for nitrate.

Coliform bacteria are common in the environment and are generally not harmful. However, the presence of these bacteria in drinking water may indicate that dangerous disease-causing bacteria are also present. It is important that private wells are regularly tested for coliform bacteria. There should be no coliform bacteria in your drinking water.



Because fresh water is lighter that salt water, it floats on top of it. Along the coast, you find what is called a " fresh water lens" where the fresh water floats on top of the salt water. Private wells along the coast will tap into this fresh water lens as a drinking supply. Salt water can get into the fresh water lens, making it unusable for drinking.



For more information contact Alyson McCann, Program Coordinator
Phone: 401-874-5398


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