KLD- kilo litres per day or cubic meters per day. It is assumed that a person uses 150 lts of water per day. PE- Population or Person Equivalent. Each person produced 60 gram BOD (biological oxygen demand) and 120 gram COD (chemical oxygen demand) in a day when engaged in defecation, urination, shower, clothes washing and other household activities. When this is diluted or equalized in daily water consumption and disposal it become BOD= 400 mg/l and COD= 800 mg/l. With these as preconditions sewage treatment plants for small communities are designed. In the case of water saving appliances in buildings, the PE should be kept the same and the equalized load should be altered. For example, if a community disposes only 100 lts/ day, then the design basis would be for BOD= 600 mg/l and COD= 1200 mg/l. It is important for designers to make these adjustments for a plant to perform.