Describe how saltwater intrusion can affect drinking water quality in coastal areas.

• A. Saltwater intrusion generally cleanses drinking water making it safer.
• B. Saltwater intrusion has no effect on coastal groundwater wells.
• C. Saltwater intrusion reduces salinity and makes water taste better.
• D. Saltwater intrusion raises salinity, changing ion concentrations, taste and potability, and can corrode infrastructure.

Answer: (D)

Saltwater intrusion happens when seawater moves into coastal freshwater aquifers, often due to over-pumping, tides, or rising sea levels. When this salty water mixes with groundwater, the overall salinity and ion concentrations in the drinking water rise. That makes the water taste salty and can push ion levels (like sodium and chloride) above acceptable drinking-water limits, reducing its potability. The higher salinity also accelerates corrosion of metal pipes and other parts of the water distribution system, and it can cause scaling or mineral deposition that affects infrastructure and treatment efficiency. In short, intrusion makes water less safe to drink, tastier salty, and more corrosive to pipes and facilities. The idea that it cleanses water, or that there is no effect, or that salinity would decrease, doesn’t match what actually happens—saltwater brings more salts, not fewer.