None of the methods that are commonly used for routine determinations of the microbiological content of water are entirely satisfactory. Each method has one or more shortcomings, but the methods in use are the best that are currently available. Many new modifications and adaptations of old methods are being developed. A vast array of different techniques, based on innovative applications of biotechnology and often on sophisticated instrumentation, are becoming available. These developments will result in more rapid, sensitive, and/or accurate analyses, frequently at less cost to the analytical laboratory. The present status of some recently described analytical techniques will be discussed. Examples of applications will be cited. The need for more instrumentation and greater expertise in the performance of microbial water analyses will be discussed.