There is provided a method for monitoring a vacuum system such as that used in a dairy milking system. Several independent measurements are made whereby a long term degradation of the vacuum pump or other component in the vacuum system may be identified before system performance drops below acceptable limits. Baseline data generated when the vacuum system is known to be in good working order. The baseline data is used to compare operation of the vacuum system. An alarm signal or other indication may be generated to alert an operator that vacuum system performance has degraded beyond an acceptable limit. Such predictive failure techniques allow maintenance to be performed on the vacuum system long before performance degrades to a point where a system becomes inoperative.