A rapid characterization technique for natural organic matter (NOM), specifically designed to study water treatment processes, is reported. The organic carbon concentrations of four NOM fractions, very hydrophobic acids (VHA), slightly hydrophobic acids (SHA), hydrophilic charged (CHA) and hydrophilic neutral (NEU), were determined. This technique could be applied to study source water organic character and link in with the operation of the treatment plant performance. This tool has the potential to guide treatment operators to control and monitor the treatment processes in the most effective way for NOM removal. A range of source water samples collected from various drinking water reservoirs in Australia, including New South Wales (NSW), Northern Territory (NT), Queensland (QLD), South Australia (SA), Victoria (VIC) and Western Australia (WA), were analyzed by this rapid characterization method. The dissolved organic carbon (DOC) concentrations of these samples ranged from 2 mg/L to 17 mg/L. The VHA fraction ranged between 17% and 82% of the DOC, SHA between 7% and 27%, CHA between 4% and 29% and NEU between 5% and 22%. This survey confirmed that organic matter in natural sources can have a wide range of variation in both concentration and character. The feasibility of using this technique to study water treatment processes was also assessed using water from Myponga Reservoir, SA. This water is generally considered a high color and high DOC water source. Raw water and alum treated samples were analyzed using this fractionation technique. The treated water samples were collected from a pilot plant operating in enhanced coagulation mode (pH controlled at 6.2) which indicated the CHA fraction was readily removed compared with the other fractions. An additional jar testing experiment using a wide alum dose range (30-180 mg/L alum) to simulate underdosing, conventional alum treatment, enhanced coagulation and extreme overdosing was conducted. The variation of the residual DOC concentration of each fraction was used to interpret the removal mechanism under different situations. The results showed the NEU fraction was hardly removed by alum treatment. The CHA fraction was readily removed in the underdosing and extreme overdosing situations. In the alum dose range covering the conventional to enhanced coagulation, both the SHA fraction and VHA fraction were readily removed. Includes 14 references, table, figures.