Contamination of recreational water in a sewered town occurs when untreated waste substances are discharged into water bodies directly or indirectly. Fecal bacteria are a category of bacteria that come from the feces of humans, domestic and wild animals. Fecal bacteria gain access into rivers and lakes through the human waste that is not treated adequately before disposal as well as from leaking sewage pipes. An overload of septic tanks during the rainy season also causes unprocessed waste to flow into water bodies. Stormwater drain pollution begins when rainwater flows over rooftops, road surfaces, construction sites, and sports grounds.
The water picks up oil, grease, and other forms of litter. The water also collects feces from animals such as dogs, cats, and other pets. In addition, unlawful sewage discharge to storm drains also introduces human wastes to stormwater. Stormwater pollution happens due to impervious ground surface and elevated velocities of rainwater. Farm runoff contamination conversely happens when rainwater moves over agricultural farms and carries with it soil deposits as well as poisonous fertilizers and pesticides.
Fast fresh contamination occurs when harmful substances gain access into freshwater bodies and alter their quality over a short period. The sources of this type of contamination include sediment deposits from farm runoff, stormwater drain contamination, and organic chemicals.
The deposition of harmful chemical substances into water bodies over a long period comprises slow accumulating contamination. The sources of such pollution include agricultural and industrial chemicals. For example, the accumulation of heavy metals such as lead and mercury leads to a slow accumulation of toxic substances in water bodies.