1.1 This turbidimetric test method covers the determination of sulfate in water in the range from 5 to 40 mg/L of sulfate ion (SO4 - - ). 1.2 This test method was used successfully with drinking, ground, and surface waters. It is the user's responsibility to ensure the validity of this test method for waters of untested matrices. 1.3 Former gravimetric and volumetric test methods have been discontinued. Refer to Appendix X1 for historical information. 1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.5 This standard does not purport to address the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.