EPA approved 17 additional methods available for analyzing drinking water samples.
• EPA Method 150.3, Determination of pH in Drinking Water
• Standard Methods 7500-Ra E and 7500-Ra E-07 for Radium 226 and 228
• Standard Method 7110 D-17 for Gross Alpha and Gross Beta
• ASTM D2972-15B and C for Arsenic
• ASTM 3559-15D for Lead
• ASTM D3645-15B for Beryllium
• ASTM 3895-15 A and B for Selenium
• ASTM 6508-15 for Nitrate, Nitrite and Orthophosphate
• ASTM D7283-17 for Gross Alpha and Gross Beta
• TECTA Method for Total Coliforms and E. coli
• Thermo Fisher Method 557.1 for Haloacetic Acids
• Tintometer Lovibond PTV 1000 Method for Turbidity
• Tintometer Lovibond PTV 2000 Method for Turbidity
• Tintometer Lovibond PTV 6000 Method for Turbidity
https://www.gpo.gov/fdsys/pkg/FR-2017-07-27/pdf/2017-15380.pdf

The US EPA gives clarification of significant figures and rounding rules. This letter was published to Dr. Edward Askew at Askew Scientific Consulting, LLC (http://www.askewscientific.org).