[The ATP concentration of drinking water compared to the colony count].

During a four months' period we have monitored the drinking water of the city of Berlin for its ATP-content and for its Total Colony Count. After concentrating the drinking water by a factor of 1000 by filtration, we obtained ATP-values which were always significantly above the blanks. The profile of the ATP-values roughly paralleled that of the Colony Counts; however, as we never observed Colony Counts nearly approaching 100 colonies/ml (which is the value not to be exceeded according to current German Law), we are unable to positively assess how the ATP-value would have behaved in samples with Colony Counts above 100 ml.