4.1 Solids, both as filterable matter (TDS) and nonfilterable matter (TSS), are important in the treating of raw water and wastewater, and in monitoring of streams.

4.2 Waste solids impose a suspended and settleable residue in receiving waters. Suspended and soluble materials provide a matrix for some biological slime and, in sufficient quantity, impair respiration of organisms. These solids may create nuisance slime beds and odors while imposing a long-term biological oxidation load over limited receiving water areas.

4.3 Knowledge of suspended and soluble materials is important in treating raw water supplies. Knowledge of solids loading can aid in determining the type or amount of treatment, or both, necessary to make the water acceptable for use. Such information may also be used to determine acceptability of water after treatment. Too little treatment may not be desirable and excess treatment costs money.

4.4 Stream monitoring is important for environmental reasons, such as compliance with discharge permits. Stream improvements, water pollution monitoring, mass wasting, algal studies, and sediment loads are but a few of the many reasons streams are monitored.

1.1 These test methods cover the determination of filterable matter, total dissolved solids (TDS), and nonfilterable matter, total suspended solids (TSS), in drinking, surface, and saline waters, domestic and industrial wastes. The practical range of the determination of nonfilterable particulate matter (TSS) is 4 to 20 000 mg/L. The practical range of the determination of filterable matter (TDS) is 10 mg/L to 150 000 µg/g. Section 20 on Quality Control pertains to these test methods.

1.2 Since the results measured by these test methods are operationally defined, careful attention must be paid to following the procedure as specified.

1.3 The test method for the determination of nonfilterable matter (TSS) must not be used when water samples were collected from open channel flow. For the determination of matter collected in open channel flow use Test Methods D3977.

1.4 The test methods appear in the following order:

1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. For a specific hazard statement, see Section 8.

1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.