Polyaluminium chloride solutions may tend to be unstable in storage particularly those having a high basicity or charge density. This may markedly reduce the efficiency of the flocculant. The invention provides an aqueous polyaluminium chloride flocculant solution containing a stabilising quantity of a dissolved boron compound or compounds such as, for example, the boric acids or salts. The stabiliser may be included during the production of the focculant or to an existing flocculant.
