A method and system of ozone treatment diverts a portion of water from a flow of water in a conduit, injects ozone into the portion to provide an ozonated portion, and recombines the ozonated portion with the flow of water in the conduit. Another method and system identifies a species-destructive reaction product of ozone with a water constituent, determines a life of the reaction product, and contacts ozone with a water containing the species for a period determined according to the determined life of the reaction product.