Parameters and contaminants monitored in drinking water and treated wastewater typically include nitrate, microbial concentrations, UV absorbance (UV254), total organic carbon (TOC), biological oxygen demand (BOD) and chemical oxygen demand (COD). Local, state and federal regulations often require monitoring of one or more parameters for environmental, health or safety reasons. In marine applications, exhaust washwater is monitored for PAH, ballast water is monitored for microorganisms and bilge water is monitored for oil, among others.