1.1 This practice is applicable to all laboratories that provide chemical and physical measurements in water, and provides guidelines for intralaboratory control and suggested procedures for reporting low-level data.

1.2 The use of this practice is based on the assumptions that the analytical method used is appropriate for the task, is either essentially bias-free or the bias is known, is capable of being brought into a state of statistical control, and possesses adequate sensitivity to determine the analytes at the levels of interest.

1.3 Further, it is assumed that quality assurance procedures for field operations such as sample collection, container selection, preservation, transportation, and storage are proper.

1.4 This practice is also predicated upon the laboratory already having established a quality control system with development of an adequate reporting system such that the laboratory's performance can be substantiated.