Oyster depuration begins after the harvest of oysters from farmed locations. The oysters are transported and placed into tanks pumped with clean water for periods of 48 to 72 hours. The holding temperatures and salinity vary according to species. The seawater that the oysters were originally farmed in does not remain in the oyster, since the water used for depuration must be fully sterilized, plus the depuration facility would not necessarily be located near the farming location. Depuration of oysters can remove moderate levels of contamination of most bacterial indicators and pathogens. Well-known contaminants include "Vibrio parahaemolyticus", a temperature-sensitive bacterium found in seawater animals, and "Escherichia coli", a bacterium found in coastal waters near highly populated cities having sewage systems discharging waste nearby, or in the presence of agricultural discharges. Depuration expands beyond oysters into many shellfish and other related products, especially in seafood that is known to come from potentially polluted areas; depurated seafood is effectively a product cleansed from inside-out to make it safe for human consumption.