The performance of activated carbon water filters, with respect to the breakthrough of dissolved organic matter (DOM) and dangerous trihalomethanes (THMs) from supplied water, has been analysed by fluorescence spectroscopy. Fluorescence spectroscopy has been demonstrated as a viable technique to monitor carbon filter performance, using the fluorescently active DOM species as an indicator. Due to the relationship between DOM and THMs, where DOM is the precursor for THM formation during the chlorine treatment of water, fluorescence spectroscopy can be used to predict the breakthrough of both species from activated carbon filters. In order to establish a versatile measurement technique, the most appropriate fluorescence excitation and emission wavelengths for detecting the DOM in water were firstly determined. These fluorescence measurement parameters were then applied to effluent water samples from carbon filters, over a total filtrate volume of 4,200 L. The total THM concentration in filtered water samples was determined by headspace gas chromatography (HSGC), with the fluorescence and HSGC results showing a high degree of correlation for the amount of DOM and THM respectively. Importantly, this correlation is observed for both of the determined fluorescence measurement parameters, highlighting the validity and versatility of this technique.