With the use of the BOD test tablet, oxygen consumption can be simulated analogously to the respirometric BOD method in distilled water. After placing one tablet to 157 mL of sample, a certain amount of oxygen is chemically bound. This creates a reproducible negative pressure in the BOD sample bottle, which can be used for functional and leak testing of the complete BOD system. Thanks to the graphic display of the BD600 and BD600GLP measuring instruments, the measured negative pressure can be read off as BOD value after 24 - 48 hours and compared with the reference check value on the blister. For the remaining measuring period of maximum 5 days, a constant BOD value is expected if the sealing of sensor heads is intact. In this way, the entire BOD system can be checked, including the stirring unit, the temperature stability during measurement, the correct sealing of the sensor heads and the correct use of the BOD5 method.