 In addition to being highly influenced by the types of organic and inorganic matter in the source water, the different species and concentrations of DBPs vary according to the type of disinfectant used, the dose of disinfectant, the concentration of natural organic matter and bromide/iodide, the time since dosing (i.e.water age), temperature, and pH of the water.Swimming pools using chlorine have been found to contain trihalomethanes, although generally they are below current EU standard for drinking water (100 micrograms per litre).