What type of water is more susceptible to pollution?

Surface water is more susceptible to pollution primarily due to its direct exposure to environmental elements and human activities. Unlike groundwater, which typically has natural filtration as it percolates through soil and rock layers, surface water bodies such as rivers, lakes, and reservoirs can receive runoff that carries pollutants from agricultural land, urban areas, and industrial sites. This runoff can include fertilizers, pesticides, heavy metals, and other contaminants, which can readily enter surface water systems.

Additionally, surface water is often subject to various societal activities, including recreation, wastewater discharges, and stormwater runoff, all of which can introduce pollutants. The limited dilution that occurs in smaller or shallow bodies of water can further exacerbate the effects of any contaminants present.

In contrast, groundwater, well water, and rainwater generally have mechanisms that provide some level of protection against immediate pollution, although they can still become contaminated under certain conditions. Groundwater relies on sub-surface filtration processes, while well water quality primarily depends on the surrounding geological formations and the depth of the aquifer. Rainwater can dilute pollutants but may also gather contaminants from the atmosphere during precipitation events or from the surfaces it collects on. Therefore, surface water is identified as the most vulnerable to pollution.