Information requirements of measurement programmes; Sampling; Basic problems and aims of sampling; Time and frequency of sampling; Overall design of sampling programmes; Procedures for obtaining samples of waters; Preparation, transport, storage, and stability of samples; The nature and importance of errors in analytical results; Random error; Systematic error; Accuracy; Effects of errors on decision making; Need to estimate analytical errors; Estimation and control of the Bias of analytical results; Detailed consideration and assessment of individual sources of Bias; Assessment of the overall Bias of analytical results; Estimation and control of the precision of analytical results; Model of Random errors; Achievement of specified accuracy by a group of laboratories; Types of inter-laboratory studies; Reporting analytical results; Reporting results close to the lower concentration limit of an analytical system; The selection of analytical methods; General precautions in water-analysis laboratories; Analytical techniques; Automatic and on-line analysis; Computers in water analysis; The scope for computing in water analysis and related activities.