1. Introduction
Water is a vital substance, as it is very essential for natural life (Lewandowska et al., 2000). An undesirable change in the physical, chemical or biological characteristics of water that will harmfully affect human life are known as water pollution (Singer, S. 1970; Akman et al., 2000; Sathyanarayanan, 2007). The aquatic ecosystem are directly or indirectly affected by pollution (Kosygin et al., 2007). Water body must be safe and free of risk factors. Risk factors related to water pollution, can be divided into two basic types: chemical and biological pollutants. Both types can always be linked to waste water resulting from domestic, agricultural and industrial activities (Subramanyam and Sambamurty, 2006; Sathware et al., …show more content…
This usually occurs when contaminated runoff and silt from laws and streets, such as fertilizers, pesticides, oil and salt, are washed into nearby water body by rain, thus causing water pollution and the accumulation of sediments .

1.2. Identifying the conditions responsible for microbial contamination of water bodies
In most of the polluted areas, the river and sewage outfalls discharging to the estuaries or marine have high levels of bacteria and viruses. Different sources of contamination are currently identified on sites where bathing activities are present or shellfish are farmed (Pompepuy, et al. 2009):
- Sewage discharges including sewage outfall, combined sewer overflows and storm water discharges. The type of treatment applied to sewage waters plays an important role in the faecal load discharged into marine waters (physical, biological or tertiary treatments).
-- Sewage network failures: many storm water events could contribute to this pollution and could trigger persistent faecal contamination even during dry weather.
-- River discharges and possible run-off from agricultural activities.
-- Other specific discharges could also come from ships, wild birds, bathers, sediments or other diffuse urban sources such as seagulls, dogs or