A composite-type solid water treatment product is provided which safely uses a halogen oxidizing agent and an active component that has reactivity thereto, which can sustain the excellent drug effect obtained by joint use of these active components, and which is very convenient to handle. In this solid water treatment product, used by eluting into water being treated, a solid preparation of a halogen oxidizing agent (A) which has a halogenated hydantoin compound as the active component, and a solid preparation (B) which contains an organic fungicide that has reactivity with the aforementioned halogen oxidizing agent are housed inside of an elution container without contacting one another.
