This first edition standard describes online turbidimeter operation and maintenance (O&M) when the online turbidimeters are used in the treatment and monitoring of potable water, reclaimed water, or wastewater effluent. This standard can be referenced in documents for purchasing online turbidimeters, can be used as a guide for verifying the accuracy and precision of online turbidimeters, or can assist utilities in establishing online turbidimeter O&M procedures. The user should ensure the environmental conditions of the application match the manufacturer-specified conditions and requirements for the analyzer. The stipulations of this standard apply when this document has been referenced, and then only to online turbidimeters used in the treatment and monitoring of potable water, reclaimed water, or wastewater effluent.