Chlorine reactivity is limited to particular chemical sites, mainly amines (nitrogen), reduced sulfur (as in cysteine, methionine, glutathione amino acids), aldehydes and ketones (often producing chloroform), and some aromatic compounds (phenols). So for some compounds there is complete oxidation as with ammonia that becomes nitrogen gas and water or urea that slowly becomes carbon dioxide, nitrogen gas and water, but for many organic compounds there is only partial oxidation or just chlorine substitution and such soluble compounds remain in the water. Organics that are not very soluble will generally get caught in the filter such as suntan lotion and some body oils.