The underground layers where water collects—known as aquifers—vary in their ability to store and supply water.

• Sand and Gravel Aquifers – These typically provide high-yield wells because water moves easily through the loose material.
• Fractured Bedrock Aquifers – In areas with solid rock, water is found in cracks and fractures. These wells can be productive, but their yield depends on the number and size of fractures.
• Clay and Silt Layers – These materials slow water movement, which can make wells less productive and more difficult to drill in.

Geology also affects how deep a well needs to be. In regions with a shallow water table, wells don’t have to be drilled as deep, making installation more affordable. However, shallow wells are more susceptible to contamination from surface sources. In areas with deep water tables, wells must go farther down, increasing drilling costs but often providing cleaner and more consistent water.

1. Mineral Content

As groundwater moves through rock layers, it dissolves minerals, affecting the taste and composition of well water.

• Limestone & Calcium Deposits – Can lead to hard water, which causes scale buildup in plumbing and appliances.
• Iron & Manganese – Common in certain rock formations, leading to reddish or black staining on fixtures.
• Sulfur (Hydrogen Sulfide) – Often found in wells drilled in shale or certain sandstones, giving water a rotten egg smell.

2. Natural Contaminants

Some geological formations contain naturally occurring substances that can pose health risks.

• Arsenic – Found in some rock formations and can leach into groundwater. Long-term exposure can be harmful.
• Radon – A radioactive gas that can dissolve into well water from granite or shale deposits.
• Fluoride – Naturally occurring in some areas and beneficial in small amounts, but excessive levels can cause dental and bone issues.

3. Vulnerability to Surface Contamination

The geology of an area also determines how easily contaminants from the surface can reach groundwater.

• Porous Soils (Sand & Gravel) – Allow faster water infiltration, increasing the risk of contamination from fertilizers, septic systems, and industrial runoff.
• Clay Layers – Can act as a natural barrier, slowing the movement of pollutants into an aquifer.

Regardless of geological conditions, proper well construction and regular testing are key to maintaining safe drinking water. Here’s what you can do:

• Test Your Water Annually – Check for bacteria, nitrates, and other common contaminants.
• Install Filtration or Treatment Systems – Address specific water quality issues like hardness, iron, or arsenic.
• Maintain a Safe Well Location – Keep wells away from potential contamination sources like septic systems, livestock areas, and chemical storage.

At Mad River Well Services we specialize in well drilling, maintenance, and water testing to ensure your home has a clean and reliable water supply. Contact us today to learn more about how geology impacts your well and what you can do to improve water quality!