<P> Most pristine rivers will have a 5 - day carbonaceous BOD below 1 mg / L. Moderately polluted rivers may have a BOD value in the range of 2 to 8 mg / L. Rivers may be considered severely polluted when BOD values exceed 8 mg / L. Municipal sewage that is efficiently treated by a three - stage process would have a value of about 20 mg / L or less . Untreated sewage varies , but averages around 600 mg / L in Europe and as low as 200 mg / L in the U.S. , or where there is severe groundwater or surface water Infiltration / Inflow . The generally lower values in the U.S. derive from the much greater water use per capita than in other parts of the world . </P>
<P> Most pristine rivers will have a 5 - day carbonaceous BOD below 1 mg / L. Moderately polluted rivers may have a BOD value in the range of 2 to 8 mg / L. Rivers may be considered severely polluted when BOD values exceed 8 mg / L. Municipal sewage that is efficiently treated by a three - stage process would have a value of about 20 mg / L or less . Untreated sewage varies , but averages around 600 mg / L in Europe and as low as 200 mg / L in the U.S. , or where there is severe groundwater or surface water Infiltration / Inflow . The generally lower values in the U.S. derive from the much greater water use per capita than in other parts of the world . </P>
bod of raw municipal sewage may be in the range of about
bod of raw municipal sewage may be in the range of about
600 mg / L in Europe 200 mg / L in the U.S.
600 mg / L in Europe 200 mg / L in the U.S.