Two differential pulse polarographic-based methods were developed in order to determine total soluble aluminium in the water used to prepare haemodialysis solutions for chronic renal failure patients. The interference from organic matter was overcome by closed-vessel microwave and high-pressure digestion procedures. The electrochemical results were compared with those obtained by using graphite furnace atomic absorption spectrometry and the correlation was excellent ( r = 0.980, p < 0.001). The detection limits for aluminium were 6 and 3 μg 1 −1 for microwave and high-pressure mineralizations, respectively. The proposed methods are a reliable alternative to graphite furnace atomic absorption methods to monitor inexpensively the water quality of dialysis units.