Disinfection of drinking water is important to prevent microbial infection and disease. However, chlorine as a disinfectant is capable of reacting with inorganic and organic constituents of water to produce hazardous chlorinated disinfection byproducts (Cl-DBPs). Brominated and iodinated DBPs (Br-DBPs and I-DBPs), which are more genotoxic and cytotoxic than their chlorinated analogs, may also be formed in the presence of bromide (Br-) and iodide (I-) in water. This paper first reviews the formation of Cl-DBPs and Br-DBPs by considering the rates of the reactions of chlorine with natural organic matter (NOM) and its model compounds. The reactions of chlorine with Br- and I- yield acids (HOBr/OBr- and HOI/OI-, respectively), which subsequently either disproportionate or react with NOM to form Br-DBPs and iodate/I-DBPs, respectively. The mechanisms of the formation of DBPs in the presence of metal ions and metal oxides (which already exist in water and are released from pipes) and nanoparticles (NPs) (input from the use of consumer products) are then reviewed. Water parameters (pH, cationic and anionic constituents, and types and concentration of NOM) also influence the production of DBPs. Plausible mechanisms of the influence of metal ions on the formation of bromate involve complexation of metal ions with moieties of NOM. Metal oxides catalyze the reactions accountable for the formation of Br-DBPs. Only a few studies have been conducted on the effect of NPs on DBP production during chlorination. More research is needed to understand the variation in NP chemistry under environmental conditions (pH, dissolution, and light), and whether NPs influence DBP formation during chlorination. (C) 2017 Elsevier B.V. All rights reserved.