Freshwater pollution is the contamination of inland water (not saline) with substances that make it unfit for its natural or intended use. Pollution may be caused by fecal waste, chemicals, pesticides, petroleum, sediment, or even heated discharges. Polluted rivers and lakes are unfit for swimming or fishing; polluted water is unsafe to drink.

Crude oil degradation and absorption were determined by measuring total petroleum hydrocarbon (TPH) in the water column and water hyacinth, respectively. The measurements were taken monthly for six months (February-August 2010). The results showed that TPH concentration in the water column in the treatment amended at 6 mg/L (0.30 ± 0.01 mg/L) was significantly lower (p < .05) than the treatment amended at 10 mg/L (0.76 ± 0.15 mg/L) but was similar to the control (0.33 ± 0.03 mg/L).