Residues of unregulated contaminants may be present in drinking water, however little is known about their prevalence in the environment. To protect human health, EPA scientists have developed a number of methods to detect unregulated contaminants.

• EPA Method 200.5 - Determination of Trace Elements in Drinking Water by Axially Viewed Inductively Coupled Plasma - Atomic Emission Spectrometery.
• EPA Method 332.0 - Determination of Perchlorate in Drinking Water by Ion Chromatography with Suppressed Conductivity and Electrospray Ionization Mass Spectrometry.
• EPA Method 415.3 Rev 1.1- Determination of Total Organic Carbon and Specific UV Absorbance at 254 nm in Source Water and Drinking Water. 
• EPA Method 415.3 Rev 1.2- Determination of Total Organic Carbon and Specific UV Absorbance at 254 nm in Source Water and Drinking Water. 
• EPA Method 521 - Determination of Nitrosamines in Drinking Water by Solid Phase Extraction and Capillary Column Gas Chromatography with Large Volume Injection and Chemical Ionization Tandem Mass Spectrometry (MS/MS).
• EPA Method 522 - Determination of 1,4-Dioxane in Drinking Water by Solid Phase Extraction (SPE) and Gas Chromatography/Mass Spectrometry (GC/MS) with Selected Ion Monitoring (SIM).
• EPA Method 525.3 - Determination of Semivolatile Organic Chemicals in Drinking Water by Solid Phase Extraction and Capillary Column Gas Chromatography/Mass Spectrometry (GC/MS).
• EPA Method 528 - Determination of Phenols in Drinking Water by Solid Phase Extraction and Capillary Column Gas Chromatography/Mass Spectrometry (GC/MS).
• EPA Method 529 - Determination of Explosives and Related Compounds in Drinking Water by Solid Phase Extraction and Capillary Column Gas Chromatography/Mass Spectrometry (GC/MS).
• EPA Method 530 - Determination of Select Semivolatile Organic Chemicals in Drinking Water by Solid Phase Extraction and Gas Chromatography/Mass Spectrometry (GC/MS).
• EPA Method 535 Rev. 1.1 - Measurement of Chloroacetanilide and Other Acetamide Herbicide Degradates in Drinking Water by Solid Phase Extraction and Liquid Chromatography/Tandem Mass Spectrometry (LC/MS/MS). 
• EPA Method 537 Rev. 1.1. - Determination of Selected Perfluorinated Alkyl Acids in Drinking Water by Solid Phase Extraction and Liquid Chromatography/Tandem Mass Spectrometry (LC/MS/MS). 
• EPA Method 538 - Determination of Selected Organic Contaminants in Drinking Water by Direct Aqueous Injection-Liquid Chromatography/Tandem Mass Spectrometry (DAI-LC/MS/MS).
• EPA Method 540 - Determination of Selected Organic Chemicals in Drinking Water by Solid Phase Extraction and Liquid Chromatography/Tandem Mass Spectrometry (LC/MS/MS).
• EPA Method 543 - Determination of Selected Organic Chemicals in Drinking Water by On-line Solid Phase Extraction - Liquid Chromatography/Tandem Mass Spectrometry (On-line SPE - LC/MS/MS). 
• EPA Method 544 - Determination of Microcystins and Nodularin in Drinking Water by Solid Phase Extraction and Liquid Chromatography/Tandem Mass Spectrometry (LC/MS/MS).
• EPA Method 556 - (jointly developed with OGWDW) - Determination of Carbonyl Compounds in Drinking Water by Pentafluorobenzylhydroxylamine Derivatization and Capillary Gas Chromatography with Electron Capture Detection.