The quality of output from an environmental sampling project is limited by whichever is the weakest component-sampling or analysis. Progress in analytical protocols, including the development of new and more sophisticated techniques described elsewhere in this handbook, results in the taking of samples increasingly becoming the quality-determining step in water quality assessment [1, 2]. Conclusions based on laboratory results from the most careful analysis of water samples may be invalidated because the original collection of the samples was inadequate or invalid. Poor sampling design or mistakes in sampling technique or sample handling during the sampling process inevitably lead to erroneous results, which cannot be corrected afterward [3-7].