Organic wastes, improperly disposed, cause problems of oxygen depletion, pollution and foul smells.
The breakdown and decay of living material requires oxygen. The amount of oxygen consumed by a given amount and type of organic material when broken down in nature is know as its biological oxygen demand (BOD). Chemical oxygen demand (COD) is the even greater amount of oxygen that would be needed to completely oxidize the material in a laboratory. Both indices are used as measures of the organic content of waters.