Toxic cyanobacteria (blue-green algae) have now been reported in 27 countries and are found on all continents, including Antarctica. Drinking water authorities world-wide are faced with the challenge of treating contaminated water, or the possibility of a toxic bloom occurring sometime in the future. Knowledge of reliable treatment options, applicable in a range of conditions, for the toxins produced by cyanobacteria (cyanotoxins), is of crucial importance to the international water industry. In this work a range of treatment options was investigated for the most commonly identified algal toxins in drinking water sources, the microcystins. A study of the adsorption of cylindrospermopsin onto six powdered activated carbons (PACs) is also reported. Includes figures.